How to maintain
and repair a boat:
tools, spares,
techniques, troubleshooting

... [since 1994] only EPA-certified technicians can buy refrigerant. ...

... Since 1993, the only people allowed to open a refrigeration system [coolant loop] have been certified technicians. Any procedure beyond a simple topping-off clearly constitutes "servicing" or "opening" an appliance and as such [must be done by an EPA-certified technician]. ...

I ordered my 2.8A (336W) Hejet plastic welder, plus the "high speed tip" plus two pounds of rods of each of the six most common plastics. That is probably a lifetime supply for a recreational user like myself. It came a few days later as promised. I had also ordered one for my brother, and it arrived at his house on time as well. I used both welders and they behaved identically, so Hejet quality control is at least satisfactory.

The gun itself is a glorified heat gun, apparently with very precise temperature control. It is made of chromed steel and plastic. Considering it won't be used that often, it would be safe on a boat if kept in a dry container.

The instructions that come with the unit are pretty pathetic. I expected at least a color booklet describing how to weld, or even better a short video, but there were just a couple of xeroxed pages giving a general overview of the process. You're basically on your own to learn by experimentation. The instructions do say that it takes about 30 minutes of practice to get the hang of it, and they were exactly right. After a frustrating half an hour with my brother's gun, I was able to weld one piece of rod to another piece of rod (of the same kind of plastic of course) and have the weld be stronger than the rod itself. That is the indicator of success, says the instructions, and it is quite easy once you learn the look and feel of the process. Both the Hejet people and now I too strongly recommend buying the "high speed tip", because it makes the process vastly faster and easier.

Anyway, after the practice session I went on full alert, waiting for something made out of plastic to break so that I could fix it. ;) The opportunity presented itself four days later. My wife's HP Palmtop computer cover hinge finally gave out, after going six months in a nearly-broken state. She immediately began agitating for a new palmtop computer, since hers really wasn't usable with the broken cover. Somewhat nervously, I attempted my first 'real' weld on the palmtop. I guessed that it was made of PVC plastic, which turned out to be right. (The welder comes with decent tips on how to figure out what kind of plastic a thing is made of.) Then I fired up the gun and just did it, and was fairly surprised that I got it right on the first try, without melting the surrounding case plastic much at all. The hinge works perfectly now, and I was unable to pry off a piece of welded plastic from the case with a razor, so the bond was good. Indeed, this is the first time that a gimmicky tool has actually, truly paid for itself on the very first usage.

Wifey was impressed, as you might imagine. The idea of actually repairing a broken plastic item is surprising to most people. The only difference between my weld and that done by a pro, I think, is the aesthetics ... mine is perfectly strong but not real smooth, even after a bit of filing. It's still fine though.

So plastic welding is for real, and the Hejet tool works as advertised. I don't have any experience to know if other types of plastic welders (e.g., soldering-gun type) work better, but I don't think they do: hot air seems to be the simplest way to uniformly heat a controlled area of two separate pieces of plastic. Of course, hot air welders are four times the price of soldering- gun welders. :(

Eventually, I'm going to build some polyethylene holding tanks and buoyancy tanks in the odd shapes needed on board my boat, now that I'm certain that I can make genuinely strong welds in plastic. In fact polyethylene seems to be one of the easiest plastics to weld.

> I was given a 1972 trawler which has not been in
> the water for over 10 years, and needs a considerable
> amount of work on hull, cabin and engines.
> What book should I get to help me ?

You might want to consider the Bible. I think you're gonna need a lot of prayers to get you through this one. ...

... The stanchion job is perfect for practice: you are replacing rotten balsa wood, so ANYTHING you do will improve the situation.

0) Clean everything w/ acetone. Wear breathing mask.
1) Put tape over bottom hole.
2) Fill with un-thickened epoxy (this wets out the surfaces inside hole).
3) Pull tape, catch epoxy that leaks out, clean up spills.
4) Put new tape over bottom hole, thicken epoxy.
5) Force as much epoxy into hole as possible, w/o popping tape off bottom.
6) Repeat as necessary.
7) Go drink ONE beer. You won't need any more after all the acetone fumes you've been inhaling.

Make up the joint using spacers to insure an adequate layer of sealant between the base and the deck. I use 1/8" diameter pieces of wire.

I first make up the joint dry with the fasteners to make sure everything fits well. Draw a pencil line around the joint. Take it apart and put blue masking tape on the deck at the pencil line, and around the edge of the object to be bedded. It is much easier to apply the masking tape than it is to clean up the excess without masking tape.

Then tape down the pieces of wire to the deck with just a little of the wire over the line so that it is between the deck and the object. Then put down a generous bead of bedding and make up the joint. The wires insure that there will be exactly 1/8" of bedding between the object and the deck. The next day remove the tape and wires and clean up. Do not put any load on the joint that will squeeze the bedding out. You might try methods that will remove the tape and excess bedding but leave the wires in place. Wait until the bedding is cured to a quite firm state and then tighten up on the fasteners.

The object is to make a perfect formed-in-place gasket 1/8" thick and then put it under compression.

...

The wrong thing is to squish all or most of the bedding out. This will leave a very thin gasket so that the slightest movement of the object will break the adhesive seal of the bedding material and allow water to wick in.

• Silicone:
  • Flexible.
  • Chemically impervious (fuel and oil resistant).
  • Compatible with plastics.
  • Good for separating dissimilar metals.
  • Cures rapidly.
  • Weak bonding, especially to wood.
  • Can't be sanded or painted.
  • Needs UV-inhibitors and mildewcide mixed in; only use marine-grade.
  
  
  
• Polysulfide (e.g. Boat Life's Life Calk, 3M 101):
  • Can melt some plastics, acrylics, Lexan, vinyl.
  • Bad for separating dissimilar metals.
  • Less elastic than silicone.
  • Cures slowly.
  • Can be sanded or painted.
  • Can last 20 years.
  • PolyGone removes polysulfide caulk.
  
  
  
• Polyurethane (e.g. 3M 5200, SikaFlex 292):
  • Extreme adhesion; near-permanent bond (3M 4200 less permanent).
  • Cures very slowly.
  • Diesel fuel softens/damages 5200.
  • After you open and then close a tube of 5200, the whole tube solidifies in a few days to a couple of months (depending on who you ask).
  • 5200 can't be sanded.
  • To remove polyurethane/5200: Anti-Bond 2015, or turpentine (soft while wet with turpentine; when dries, it's hard again), or Lestoil floor cleaner.
  
  
  
• Flexible Epoxy (e.g. Flexbond Marine Epoxy):
  • Expensive.
  • Near-permanent bond.
  • Cures underwater.

• Silicone: shorter lifespan, can peel loose, damages some plastics.
• Polysulfide: best for ports, deck hardware, everything.
• Polyurethane: too permanent for most jobs.

... think of silicone as a gasket material instead of a sealant ... because it depends upon mechanical compression to maintain its seal, silicone is also a poor choice for sealing hardware on a cored deck ...

... You can - and should - use polysulfide to bed almost everything. ... One caution: do not use polysulfide to bed plastic.

... Consider polyurethane an adhesive [that forms a permanent bond] rather than a sealant.

BoatLife's Life Seal: part silicone and part polyurethane. ... this mixture promises a longer-lasting seal for deadlights and other plastic fittings where compression of the sealant cannot be assured. ...

Use 3M 5200 when bonding to metal; the bond can be broken later by heating the metal.

Don't use 3M 5200 when bonding two pieces of fiberglass/plastic together; the only way to get the bond apart later is to saw down it.

... 5200 and 4200 do not weather well in the sun -- mine started chalking and giving off black marks within a few months ...

... let the 4200 cure well then sand lightly and paint. I have done this before and it works out well. The 4200 or 5200 is fine after years. It is only the UV that gets to it.

[When I complained about a cap that split and let all of my caulk dry in the tube:]
Buy a 99 cent toilet bowl wax seal, the very cheapest possible, and dip your caulk tubes into it when you finish a job. The wax will seal the end better than any cap can, and you can just squish it out later.

[After he told me not to use silicone to bed metal hardware
or teak strips onto fiberglass deck:]
> Okay, so when should I ever use silicone ?

Silicone is good for metal, glass, lexan, abs plastics, etc.

> Is polysulfide harder to get off later ?

Not really, polysulfide may seem harder to remove, but silicone leaves a residue behind that can cause polysulfides to not stick real well.

I haven't purchased silicone sealant for this boat - ever.

> When we used BoatLife polysulphide, we had to re-do the entire deck
> because the stuff had cracked inside.

Wow! Same thing happened to us! We got BoatLife to replace the stuff that didn't work (although they didn't admit liability of course, and the labor involved was tremendous) but in the end we decided not to chance a complete product failure again and went with Teak Decking Systems SIS 440, after testing about 5 different products on the fantail and waiting a year to see what held up best. In fact, we just finished the job 2 weeks ago. We may even consider using the same stuff to bed the deck hardware. It's a joy to work with.

Lifeseal is a mixture of polyurethane and silicone. It is an excellent sealant for Lexan-Fiberglass ports.

There is a known chemical incompatibility between CETOL and Boat Life 2-part polysulfide caulk. The CETOL when applied over the caulk eventually breaks it down. You end up with a sticky mess, the caulk "bubbling" out of the seams like tar on an old ship. Heat (hot days) seems to accelerate the problem.

... After struggling a number of times through the process of removing the old caulking, I found a "magic" product made by Boatlife called Release -- an adhesive and sealant remover. Costs about $16 for a 16-ounce spray bottle. Spray it on the old caulking (even at the top of the windows), wait a couple of minutes and you can almost pull the old stuff out in a string, with some help of a skinny putty knife. It even works on relatively new caulking ... If you spray it on and then change your mind, let it dry and it re-seals. ...

Marine Sealants in a Nutshell

One thing you have to do on boats is bed hardware. This has to be done on a regular basis, especially with hardware that is under heavy cycling loads, like cleats. However, using the right sealant can make this task much simpler.

Most people are familiar with silicone caulk, since it is the most commonly used type of caulk in normal household repairs. However, while certain Silicone-based bedding compounds are excellent for bedding ports, most of the time, silicone caulks really serves no useful purpose on a boat beyond bedding ports and covering the ends of cotter pins.

In most cases, on a boat, you want a sealant that will adhere to the two surfaces being joined — whether it is a through-hull and the hull or a cleat and the foredeck. The sealant should have a fair bit of elasticity so that it can stretch when the hardware moves or shifts under load without detaching from either side and breaking the seal.

For deck hardware and through-hulls, countersinking the fastener holes is probably one of the best things you can do, since it gives the sealant a natural place to form an o-ring-like seal.

There are four major classes of bedding compounds/sealants used on a boat:

• Polyurethane-based sealants such as 3M 4200 and 5200, SikaFlex 291, 292, 295, 296.
• Polysulfide-based sealants such as LifeCaulk and 3M 101.
• Silicone-based sealants, such as Dow 295.
• Butyl Rubber Glazing tape — this is not butyl rubber caulk.

Each of these sealants has specific pros and cons.

Polyurethane-based sealants are basically adhesives with sealant properties. They are often very permanent and have very strong adhesion strength, and can be used both above and below the waterline.

3M 5200, a polyurethane sealant commonly found in marine chandleries, is basically for all intents and purposes a permanent adhesive and should not be used on boats for the most part. 3M 5200 has a bonding strength so high that it can often cause delamination or damage the gelcoat when you try to remove hardware bedded with it.

However, polyurethane sealants have some of the best materials compatibility, so the less aggressive ones, like 3M 4200, are very useful. SikaFlex 291 and 292 are probably better choices, but usually more difficult to find. For bedding ports, Sika 295 or 296 can be used in place of Dow's 795 Silicone.

Be aware that using a polyurethane sealant can make removing hardware much more difficult than using other sealants. There is a solvent, called DeBond 2000, which can be used to weaken the bond if you need to remove hardware that was bedded with 5200. One other issue with the polyurethane sealants is that they have a relatively short shelf-life, once opened. This is due to their being moisture-curing compounds, and once exposed to the moist sea air ... they start to cure ... and you eventually end up with a solid tube of cured sealant.

Polysulfide-based sealants are the best general-purpose sealants for marine use. They are not as aggressively adhesive as polyurethane-based sealants and generally a bit more elastic and flexible. They can be used both above and below the waterline, like the polyurethane sealants, and are better than polyurethane-based sealants for hardware that has to be re-bedded more frequently.

Polysulfide-based sealants are excellent for bedding wooden items, like rubrails and cockpit coamings, since it adheres fairly well to teak. The fact that these items often need to be removed for periodic re-finishing makes it ideal IMHO.

The main drawback of polysulfide-based sealants is that they tend to attack many common plastics — most commonly acrylic and polycarbonate. They are safe to use on acetal, delrin, nylon, and marelon fittings though. If you're not sure what the fitting is made of, don't use polysulfide-based sealants with plastic fittings.

Silicone-based sealants aren't really sealants IMHO. They're really gasket materials, and need to have a minimum thickness and be kept under compression to work properly. Silicone-based sealants should only be used in above-the-waterline applications.

The only structural silicone sealant that I generally recommend is Dow 795. This is a structural adhesive which is generally recommended for bedding ports. It is not your common silicone caulk. However, beyond the very specific use of bedding acrylic* ports, it should not be used on boats.

Aside from bedding acrylic and polycarbonate ports, and certain plastic parts, like Beckson ports, and covering the exposed ends of cotter pins — it really has no place on a boat — primarily due to the residual silicone contaminants silicone can leave behind. These contaminants are almost impossible to remove thoroughly, and will prevent other sealants and paints from adhering to the surface properly. Even strong adhesives, like epoxies, have trouble bonding if the surface has silicone contaminants on it.

One other use of silicone is for sealing potable water tanks. However, I highly recommend that you use only NSF approved silicone sealants for potable water tanks and systems. These will not have any toxic components, unlike some of the other marine-grade sealants which may contain isocyanates.

Some silicone sealants are acid-curing and should never be used on metal. These are generally easily detectable by the strong vinegar smell caused by the acetic acid that is contained in them.

The last sealant is butyl rubber glazing tape. This may be one of the most versatile sealants you can use on a boat. However, it has the weakest adhesion and tensile strength and highest elasticity of any of the sealants. It is also the most easily affected by other chemicals, as it doesn't cure like the other sealants do.

Unfortunately, many petrochemicals and common solvents will dissolve or damage it. Because of its sensitivity to petrochemicals, I generally don't recommend it be used below the waterline.

It is great for bedding deck hardware, especially things like chainplates, where a certain degree of movement is unavoidable. It has the greatest materials compatibility of all the sealants and is also probably the least expensive of them.

One major advantage of butyl tape, since it doesn't cure, is the working life. This makes it ideal for bedding things like traveler and genoa fairlead tracks. The lower physical strength of butyl tape generally isn't an issue due to the large number of fasteners generally used on these tracks.

Other Sealants

Two other sealants of note for marine use are 3M 4000 UV and BoatLife's LifeSeal.

3M 4000 UV is a polyether based sealant, and as such is generally fairly well suited for use with plastics. However, it is not recommended for below-the-waterline uses. It cures relatively quickly, as it is tack-free in under half-an-hour and cures in 24 hours or so.

BoatLife's LifeSeal is a hybrid polyurethane/silicone sealant. As such, it isn't as permanent as a pure polyurethane sealant, but is more an adhesive bedding compound than a pure silicone material. However, it still has many of the contamination issues that any silicone based sealant will have. It also is fairly inelastic, and IMHO, 3M 4000 UV is a better choice.

*Most marine ports should be made of cast acrylic, rather than polycarbonate, due to several physical characteristics that make polycarbonate less suitable. First, polycarbonate tends to deform under load, which can cause it to shear the adhesion of the glazing to the underlying sealant. Second, it is less scratch and UV resistant than acrylic. Third, it is more difficult to find polycarbonate in UV/scratch resistant versions in sizes thicker than 1/4".

Not many products specifically targeted at this use.

Some hull types (wood, aluminum) very hard to bond to.

No products were entirely satisfactory: some too slow-curing, some too weak.

Bio-Fix 911 cures quickly but only moderate holding. Use duct tape or wedges to hold a plate on, and Bio-Fix 911 to seal joint.

Epoxy sticks (AquaMend, QuikAluminum) good for filling small holes.

Replace stores of products every year or two.

Extraction of broken bolts and studs:

OK, here is the broken stud 101, that I use, and have used successfully many many times. Credit goes to Graham my Audi technician from Cape Town who taught me this. The smallest bolt I have extracted is 6 mm and the biggest 22 mm. It's not cheap but it works.

1. Get a flat-ended pin punch, and beat the end of the stud square and flat, use many light taps, like hundreds!
   
   
2. Get a centrepunch, and even if you have to grind it especially, punch a dot in the centre.
   
   
3. Start drilling with very small bit, watch your feeds and speeds, make sure there is swarf coming out the hole otherwise the metal you are working is work-hardening (then give up) this is especially true on stainless.
   
   
4. Keep a cool tool! Lube the cutting edge, go get out there and buy the cutting oil in a spray-can, it's worth it!
   
   
5. Now go out and buy a torx or spline drive socket or driver. For those who don't know what it is, it's either a socket that fits on your socket set that has a very hard tip consisting of six sharp points in the case of torx, or 12 in the case of a spline, or a screwdriver type. They are numbered, like Torx #6 etc. Buy one that is smaller than the ID or root diameter of the thread in practice 1/3 the OD (leaving a third of "meat" either side of the hole otherwise it will shear off again).
   
   
6. Examine the torx from the end, see that there is an inner and outer diameter ... (the valleys and peaks of the points) your final hole is the same size as the INNER diameter, like it won't fit right ... right!
   
   
7. Take the torx to your bench grinder, and grind the tip, without overheating it, so that it is 90 degrees and has SHARP points not the nice shamfered end as new which aids getting it into the torx head screw.
   
   
8. Hammer the thing into the hole you have meticulously prepared, the points should cut their way into the metal of the screw AND NOT EXPAND IT so that it is even tighter!
   
   
9. Attach your handle and unscrew the little bastard!

Get some glazier's putty, children's modeling clay or electrician's caulking compound and build a small dam around the nut or cap screw that is frozen in time. The stuff needs to be oil-based, not water soluble, such as Play-Doh or other washable goo. Degrease the area, and remove any penetrating oil you might have tried before.

The little dam needs to be molded so that it will keep the nut, screw head, stud end, or whatever is stuck, submerged in at least two ounces of liquid. Now fill the reservoir with regular Pepsi-Cola. Coke and some of the other colas and soft drinks may work, but Pepsi has more phosphoric acid, which is what does the job, along with the carbonic acid and something in the formula that makes the liquid penetrate into the threads and cracks.

Check each application for leaks and leave it alone for about six hours. If you have several stickers, make as many dams as you need. Check in an hour or so for leaks, but leave it alone and let it work. Don't loosen the dam just yet, unless you cannot get the wrench on the nut. In most cases the fastener will unscrew as if by magic. If it is still frozen, try another application of fresh Pepsi. Six hours later if it still will not move, then you need a nutcracker or cold chisel. Your problem is beyond the capabilities of channel locks and Vise-Grips.

Another possibility, which has caused many salty words from mechanics and sailors alike, is that there may be a hidden problem that even Pepsi cannot dissolve. If you don't know the history of the machinery or the fastener, consider this. Some well-meaning soul may have applied a LocTite compound to the joint. It might as well be welded.

LocTite is a family of anaerobic, cyanoacrylate resins which have unusually good penetrating qualities and which harden when out of the presence of air. If you think this may be the case, done either at manufacture or during a repair, get an ultra-violet "black-lite" source and in a darkened space, illuminate the subject in "black-lite". Any traces of LocTite will fluoresce in a color that will indicate the grade of LocTite that was used. Get out your propane torch or a really big soldering iron. The joint or fastener will need to be heated to about 350 degrees F before it will break down the resin. The fastener will need to be unscrewed while hot.

Never apply anaerobic thread and bearing sealant compounds without first considering whether you or some poor unsuspecting person will come after you and end up losing their temper, manners, and religion over a very tight joint.

On the matter of penetrating oil, most of the naphtha-based graphite suspension products have been withdrawn because of the carcinogenic qualities of the liquid. An alternative is Oil of Wintergreen, sold at the pharmacy, but try Pepsi first. Buy it by the case for flushing out fresh and seawater corrosion in motor blocks, pumps, and circulating systems. Good stuff.

Aluminum has twice the expansion of steel. To get the wheel off a shaft, I would apply a gear puller, with lashings or spiral clamps for security, put as much tension on it as you dare, then apply significant heat to the hub of the wheel. Personally, I find that lots of heat applied quickly, before it has time to spread, works best. ... invite all your friends and ask them to each bring a propane torch. Apply all the torches at once. When the heat is as high as you dare and the thing still does not pop off, whack the end of the screw on the gear puller with the biggest hammer you can find. If that doesn't do it then cut the hub in half with a hacksaw and weld it back later.

Aside about hammers. When you want to move something, use one great whack with a big hammer. Medium whacks with a medium hammer only move metal around. If any particular whack does not move the parts, many of the same force will not do it, and often will make the situation worse by peening metal around.

If you are going to do much cutting or machining of plexiglass, ask your supplier to give you cast acrylic rather than the more common and somewhat less expensive extruded acylic. The cast material does not melt when cut. It's a joy to work with compared to the extruded stuff.

Try a laminate blade and a jig saw (the teeth set downward) and go very slow to avoid melting the plastic. Apply tape to the base of the saw to avoid scratches. It worked for me. Plexi shops use a hollow-ground band-saw blade. Also to drill screw/bolt holes in plexi, some shops will sell you a bit for $5 to do the job.

A sabre saw with coarse tooth blade running at low speed works well. Too high a blade speed will melt the plastic. A single speed saw can be controlled with a lamp dimmer just like a lamp would be. Lower speed works better for metal cutting also. The cut edges of the plastic can be "polished" with the adhesive used to cement acrylic together. A smooth edge to start with by filing or sanding helps a lot. I leave the protective paper on the plastic for all of the fabrication, taking it off just at assembly.

You should "polish" the edges with a little heat. Enough to melt the sharp corners and edges but not enough to distort the surfaces. It can be done with a propane torch with a little practice. Use some of the scraps and hold the torch well away. Once the rough edges turn shiny that's enough heat. It's not too hard once you get the hang of it.

I have found that using a coarse carbon tipped blade in a table or circular saw just melts the cut and leaves a huge mess. If I move over to a fine-tooth plain steel blade, it cuts it like butter, little chips fly off, no-melting, leaving a nice clean cut surface. Last blade I bought was $6.50 at Home Depot. Well worth the investment.

I have done this for years, cutting new acrylics for hatches. Use a router, double-sided tape your template to the acrylic and rout around it. Flawless operation. No chipping cracking or other problems.

There is a special plastic cutting blade for circular saws ... it looks like gritty sandpaper on each side. I've used the same blade for about 15 years. The blade doesn't heat the plastic too much. Used it for corian, avonite, lexan, pvc plate and pipe. You can cut outside curves fairly easily, inside curves are a pain. ...

There is nothing special about drilling Lexan. If drilling material thicker than about 1/4" it may be worthwhile to use a squirt bottle to use a little water to cool the material, or drill slowly since you can melt the plastic onto the drill bit if it gets too hot; same with Plexiglas or Lucite. Both are somewhat brittle so be sure to have a piece of wood behind the work if drilling in place or beneath if doing on the bench.

I own a Kawasaki Concours sport touring motorcycle and when I bought it it had a cloudy almost milk-color plastic windshield. You could not see through it. I used regular auto rubbing compound to rub it out and it became very clear. That was several years ago and it is still in good shape. Start with the most gentle and if that doesn't do it then work your way up to the next heaviest grade. Mine did well with the least abrasive, but took a couple, maybe three applications with soft cloth rubbing the abrasive on and off with a clean one. Be sure to keep the buffing cloth very clean.

A couple of other 'cheap tricks' you can try ... a bit of toothpaste will tell you if you can reasonably restore clarity by polishing. If it seems like that works then you may want to invest in a better polish and go for it, but plain old toothpaste will clean and polish a lot of stuff.

I also like to use an "Island Girl" product (on the boat and name escapes me) to rejuvenate clear plastics. Even my badly crazed hatches were much clearer after a good soak in this stuff and the pre-cleaner removed the haze from the side ports easily.

... clean with soap and water, do not use stuff like acetone or similar cleaning agents, only use specified polishing compounds when removing scratches.

Never, ever, let anyone near Plexiglass (Perspex) with paint stripper.

Re: Acrylic (PLEXIGLASS) or Polycarbonate (LEXAN, MAKROLON):

Acrylic has a harder surface but there are polycarb sheet products available with an abrasion-resistant coating applied to the surface. Such as GE's Lexan coated materials, but its only a coating, so once the coating goes ...

The polycarb coated product is very tricky to form without crazing or bubbles showing up on the bends.

Acrylic is fairly easy to bend, form or fabricate and offers nice clear bends. Acrylic also is easily polished, especially edges, where polycarb doesn't polish up well.

Acrylic is more rigid than polycarb; way back in the 70's a lot of dance floors were built from Acylic.

Acrylic is very tough and break-resistant, though notch-sensitive. Hence, cracks can emanate from unfinshed mounting holes or rough edges. Polycarb has a high degree of resistance to any impact, even on unfinished mounting holes or edges, and is very close to unbreakable.

Acrylic is also cheaper than polycarb.

Acrlic has excellent UV resistance. Polycarb products don't, though some are available with a UV coating; again it's just a coating and causes problems in forming.

First, I read up on fiberglass repair in two or three of the fix-up-your-old-boat books ("This Old Boat" by Don Casey, and "The Boat Repair Manual" by George Buchanan).

I then bought the large gelcoat repair kit from West Marine (later saw nearly identical kit in WalMart for about half the price), an additional qt. of white gelcoat with catalyst, a tube of tint (my topsides are sort of buckskin color), and a qt. of PVA.

I've discovered a couple of things that I don't remember reading much about:

Matching gelcoat colors was really hard for me. It took a lot of patience, and I threw out several batches after screwing up the color beyond recovery. I tinted in approx. 8oz. batches (large enough to complete my repair), and catalyzed in much smaller quantities.

For filler putty, I used tinted gelcoat thickened with Cabosil (coloidial silica?). It worked great.

To get the air-inhibited gelcoat surface to harden, I brushed on PVA mold release just after the surface was stiff enough to resist brush strokes.

At some point in tinkering with the cosmetic appearance of the repair, I paused to have a debate with myself about how many hours I was willing to invest in exchange for what level of perfection on a 20 year old boat. Don't forget to have this discussion with yourself, maybe more than once.

I wet sanded the repairs with 180 and 220, and the entire hull from shear to bootstripe with 320, 400, 600 by hand. I then power buffed with red rubbing compound using a multi-speed 7" disk sander/buffer.

So far I'm really pleased with the results (and modest too!). I'll probably power polish with fine white polishing paste before waxing.

Gel coat repair kits are available at marine stores. First sand the base area with fine sandpaper, then clean with acetone on a rag [but Janet aka RavenIV says "never use acetone to clean after you sand, it can compromise the exposed resin. Instead either blow it clear or vacuum the area."]. Don't begin building up the gelcoat patch - first you need to practice getting the color match. No matter what you do, however, it will never be exact. Even if the color gets matched today, six months from now it will slightly discolor with ultraviolet light exposure, making a small change in color. If it's a small area, don't worry too much about it, just do your best. Start blending the pigment with the catalysed resin, put it on a piece of cardboard and let it kick off. When you get a feel for the correct pigment blend, make a little extra and "putty" it on to the affected area. Wipe off the excess while it's still "green" or soft. Then lay a piece of saran wrap on top to seal off the air (unless the instructions of the resin tell you it has a wax additive). When the resin is good and hard, sand it down flush with the surrounding glass using fine sandpaper. Then wet sand with increasingly finer wet-or-dry sandpaper until you get to 600 grit. At this point you will have a difficult time telling it from the original. Then rub a little car wax on top to bring the shine up.

If you use epoxies [instead], you will need to paint over them to protect from further ultraviolet degradation.

There are three big mistakes people make when doing gelcoat repairs.

1) If you rout out the crack you will want to fill the area with some sort of resin based filler. Make sure that when the filler is cured that you de-wax the surface. Sanding to fair it out won't do it. You need to use a de-waxer to take the blush off the repair. If you don't you run the risk of the gelcoat not adhering or curing correctly.

2) Novices will always a) way overfill the routed area leaving a huge hump, or b) way underfill the area leaving a trench. Personally I prefer to see a trench since the hump will undoubtedly be haphazardly sanded and look worse than the original crack. Remember that the filler will shrink slightly. Don't be afraid to back off the catalyst a bit so that you have time to work the area into a nice smooth repair. If you have never worked with resins, make up a batch and practice on a piece of wood or Formica until you get the hang of it. By the way if you have never used a Dremmel tool you might want to practice with that too.

3) The color won't match. Remember that like paint, when the gelcoat cures it will change tint slightly. When I worked in the repair shops we would match the color as best we could, then smear a bit (without catalyst) onto a nearby area and wait a minute or two. This will show you how close you will be to the original color. Don't worry if it isn't perfect; it never is, but the sun and salt will soon take care of that.

With that being said, I'll add one more piece of advice. If the cracks are cosmetic, think about leaving them alone. I know boat owners want their vessels to look pristine forever, but the fact is that cosmetic cracks are inherent in gelcoat. You can't stop them from happening, and if you don't enjoy working with resins and epoxy, and cabosil (micro glass beads) forget about them. Soon you will find that they have plenty of company.

Polyester resins are laminating resins, they were designed to lay up cloth. A finishing resin is also a polyester resin but has the addition of wax, that will rise to the surface. When you use laminating resin you will notice that the surface remains sticky, this is designed this way so you can lay on another layer.

Epoxy resin is an adhesive, it is made to stick to things. A lot of the time when repair is done epoxy resins are the choice.

Now here is the rub. If I am working on a glass repair, and grind down to fresh material I would normally recommend using polyester resin rather than epoxy resin. I have found that polyester sticks to polyester better than epoxy sticks to polyester. Polyester will not stick to epoxy, if you do a repair in epoxy, then you will have to do every repair on into the future with epoxy because polyester will not stick to epoxy.

New construction. I paint a layer of polyester resin, thinned with acetone on to fresh wood so it sinks in deep. Once this is done the surface is basically a polyester surface and I laminate the cloth onto the wood with no problem, never had a delaminating problem with this method if the surface was fresh.

Epoxy resin is more expensive. I would not use WEST System epoxy. I would drive to Fort Lauderdale and use Fasco epoxy. I have used both on repairs and Fasco worked better than WEST. Joe's Auto Marine sells Fasco, I am not sure who else does.

Be careful of high solids epoxies like Steel Flex, they can be very very tough to sand. Bondo is not a marine product and should not be used. It will suck up moisture like a sponge.

If you need to do some filling on a polyester repair, just mix some resin with cabosil or micro balloons and you have something the consistency of Bondo.

Same with epoxy, mix with the same fillers and spread away.

... [Radio] soon caught a direct hit from a pint of sea-water coming in the main hatch. It did not work again during the crossing.

...

Believe it or not, all electronic circuits are completely waterproof. It is the conductivity of water, especially sea-water, sitting across the connections that makes them malfunction. The corrosive powers of sea-water can also do terrible damage if left in place for more than a few days. I took the plastic case off the machine off and ended up with three circuit boards (a computer, the radio receiver and the cassette machine), a buzzer and the loudspeaker, all interconnected and sitting in the washing-up bowl. I washed and re-washed the whole lot in several changes of cold, fresh water, washed and oiled the telescopic antenna and the battery terminals, and rinsed out the two halves of the plastic case. When I was convinced that there were no more salt crystals lurking anywhere, I put all the parts around the cockpit seats in the sun and carefully began to dry everything with clean, absorbent kitchen paper. When reassembled and then left overnight to dry completely, it all worked again perfectly.

This seems very bold at the time, "Electricity and water don't mix" we are told. I have done this to many pieces of sensitive electronics including Autohelm autopilots, digital watches and cameras. It usually works, if the corrosion has not gone too far and if you are careful not to touch any of the delicate adjustments. All you have to do is remember how to put it all back together again when it's dry!

1. Check obvious things: power, wires, fuses, switches, corrosion, connections.
2. Take apart, separating out printed circuit boards.
3. Check obvious things again.
4. Look for cracked soldered joints.
5. Wash the circuit boards; don't wash batteries, motors, speakers or displays. Wash with fresh water, scrub with water and a little dish soap, rinse thoroughly.
6. Dry very thoroughly and for a long time. Also sun-dry or put in oven at very low temperature.
7. Put it back together and try it out.

> 304 or 316 stainless: I am getting ready to
> purchase the steel for my solar panel rack and am
> wondering what the real-world difference is in
> the corrosion resistance of these two alloys.

I think 316 is the stuff to use. I made mine out of 304 7/8" ss tube. It supports four 75 W panels. It's fine, but it rusts badly, just as the pulpit rails do. If I do it over I'll use 1" passivated 316. My external chainplates are passivated 316, and they *never* rust, but I'm always after the railings.

Whatever you use, make sure the fastenings and the structure are the same material. Mixing materials, even differing grades of stainless, can invite corrosion in something that would otherwise be OK.

• Galvanized steel: "hot-dipped" usually has 3 mils of zinc; electroplated usually has 1.5 mils.
• 302 and 303 SS: crevice-corrodes freely; rusts from saltwater; never use below waterline.
• 304 SS: somewhat greater corrosion resistance than 302 and 303; rusts from saltwater; never use below waterline.
• 18-8 SS: surgical stainless; similar to 304.
• 304L SS: better than 304 for welding.
• 316 SS: much greater corrosion resistance than 304; 85% as strong as 302 or 304; use above water; if for shaft protect with zinc.
• 316L SS: better than 316 for welding.
• 321 and 347 SS: good for welding; use above water.
• Aquamet and Aqualloy: SS's for shafts; corrosion-resistant and weldable but expensive.
• SS needs oxygen to remain stainless.
• Welding SS (other than "L" versions) creates zone of mild steel around the weld.

The key to drilling stainless steel is first: a good bit, don't even attempt it with cheap bits.

The second most important thing is to drill at a constant speed that doesn't overheat the metal. This is the most important reason to lubricate (you could use water); if you overheat the metal by either going too fast or too slow, it will "work harden" and you will toast the bit. If it is a deep hole, you may not get the bit back because it will gall in place then break off or get REALLY stuck.

So keep it moving, keep it wet, and keep it sharp.

• Use low speed.
• Feed bit into material as fast as it will go; press hard. If using a bit smaller than 1/4", you should press hard enough to make the bit flex.
• Center-punch to keep the bit from wandering when starting.
• Use lubricant.
• Don't stop or slow down until hole is finished.
• Best bits are HSS jobber bits, not titanium oxide coated or special tip grind.
• Drill pilot holes.
• Using a drill press is best.
• If bit turns blue while drilling, it's turning too fast or is damaged.

The color terms yellow and red are American terms referring to the composition of the brass. Yellow brass is 33% zinc and 67% copper. Brass goes from dark reddish brown to light silvery yellow depending on the amount of zinc. The more zinc the lighter the color. Red brass is really not brass as it is an alloy of copper, zinc, and tin. It is also called gunmetal.

There are two kinds of brass on the market, yellow brass and red brass. Yellow brass is made from a variety of metals such as zinc, tin etc. This gives the brass a yellow appearance and has a life expectancy of somewhere between 10-25 years. However, red brass when compared to yellow brass has a reddish look due to the high copper content (80-85%) and has a life expectancy of 50-100 years. Note: Life expectancies assume clean water and environmental conditions. Harsh water and/or environmental conditions may shorten the life expectancy of brass products.

Be careful with StarBoard out in direct sunlight. UV degrades it over time and any stress points will split. I installed PVC (StarBoard) handrails instead of teak. After 4 years on deck, they all cracked at the screw points.