To fiberglass or not?

[KaM]

Hi guys, new to the forum, just about to start my first boat building project...


http://www.svensons.com/boat/?p=Utility/JonBoat

...and I'm currently educating myself as much as possible before I jump right in.

The build itself should be fine as I've read my way through a HEAP of threads on this forum but I do however have a question about fiberglassing that I couldn't find a definitive answer to in any previous threads, relating to a boat this size anyway (I may have missed it though).

The question is related to the following. I found this photo log of a guy who completed the exact same project a few years back…

http://www.captalrice.com/Boat%20Building.htm

My question is this - the guy above covered the entire hull with fiberglass, is that overkill on a boat this size?
Would encapsulating with bote-cote alone and finishing with clear UV resistant varnish be adequate on a project this size?
Or would a middle ground approach be best and just glass tape joins and exposed endgrain edges?

All help and advice is greatly appreciated...

Ken

[PAR]

Fiberglassing the hull protects it from abrasion much better then just coating with straight epoxy. It's not necessary on this boat. In fact you don't have to coat anything on this boat with epoxy. This said epoxy is an excellent glue, but you could even use something other then epoxy as the glue too.

The design you're building is old, developed in the 1950's. The fasteners hold the boat together according to the plans, not the glue. It wasn't designed for epoxy, nor 'glass sheathings. So, you could build as the plans say (always a good move) and the boat will be what it is, a small, disposable utility craft of limited durability, given moderate care.

Now that I've said that, you can make changes that will benefit you and the boat. The first would be to replace every nail with a screw. Nails are cheap, but they really suck at preventing vibrating and moving parts from coming apart. Screws don't have this trouble and your elbow doesn't hurt after a day with them, up close and personal. The next change I would consider is coating all the wood with epoxy. This one step will add some to the cost, but it will also dramatically increase the durability of the wood. And if you're going this route, use epoxy as the adhesive too. The screws, which replaced the nails can now be considered temporary, so you can use cheap ones, like drywall screws (my favorite).

With epoxy coated (encapsulation) wood, you can also consider removing some of the parts in this build and replacing them with fillets and biax tape. The chine, the keelsons, most of the seat risers, side battens (butt blocks), transom and stem framing would be the logical pieces. These all could be fillets and tape. This means the boat would be lighter, more water tight and you'd have less wooden pieces to buy, shape and install. Oh happy day sweet epoxy.

Lastly, the full set of upgrades wouldn't be complete without a cloth sheathing. 2 to 8 ounces as your heart desires. The lightest weight fabric will offer the minimum of protection, but it's still much better then just plywood.

On the other hand, if it was well glued together with epoxy, maybe a few coats of varnish and well cared for, she'd be cheaper and could be just as loved.

[Darce]

And the beauty of it all is that you can coat the ply with pox before you put it all together and then only glass the bits which are going to get smacked as you pull her up on the beach.

Don't forget to paint her when she's finished even though she's gonna look great all epoxy coated. Epoxy (or varnish - unfortunately) doesn't hold up too well to UV and will degrade quite rapidly unless protected by at least a coat or two of house paint

[KaM]

Thanks for the tips fellas.

PAR,
I was pretty much thinking of doing what you said. Replacing the nails with screws and using epoxy to glue it all together. With the addition of an all over epoxy coating those two things alone should increase the old designs durability greatly. I like your fillet idea too, I'll suss that out.

Darce,
That did cross my mind alright. I was thinking of reinforcing the lead edges of the bilge battens and keel with a more durable material for run ups or bumping the boat ramp. But like you say fiberglassing that area in general may be the way to go.


One more thing guys just to clear up the finish as you both mentioned different things, varnishing and painting.

This little boat is going to be stored undercover in a double garage when not in use and dropped in the water maybe once every couple of weeks for a few hours. I'm still a bit confused as to what finish is better to go for. I do want to go for a bright finish (narrows it down a bit), even though it's harder to achieve and harder to maintain. I've read that two pack varnish over epoxy is a real nightmare when it needs to be redone, which it will regularly, and that normal marine varnish is far easier to maintain over time and can even provide better results, buuuut like Darce said there's also the UV degradation factor with varnishing. What kind of degradation time frame are we talking with the kind of use I mentioned coupled with southeast Queensland sun, for both two pack and normal varnish? Are we talking weeks, or months? Also what is the result of UV degradation? Does it get sticky, peel away, get cloudy?


Any recommendations or advice?

Thanks again guys, you've already been really helpful.

Ken

[PAR]

Use a single part polyurethane instead of a two part. It's easier to apply and repair, when the time comes.

Clear coatings over wood are the most difficult to maintain. The are a few choices for clear coating, but all are much more difficult to live with then paint.

I wouldn't use 'glass as the abrasion resistant bilge strips. I'd prefer metal or hard plastic like HDPE. This need to be replaced for time to time, so make this an easy thing.

[KaM]

I was actually thinking metal for the bilge strips originally but now that you mention hard plastic I have the perfect thing rolled up and stuffed on a shelf in the garage. I knew it would come in handy for something......someday

I may yet paint, I think I'll get on with the build and see how I feel about it in a few weeks. Perhaps paint the exterior and leave the interior a clear finish. That looks pretty good generally. And it would half the clear finish maintenance headaches.

Thanks mate,

Ken

[PAR]

Most plywood looks terrible when finished bright. It has wild grain patterns from rotary harvesting the veneers and this to most looks ugly. Now some woods with really fine grain and less dramatic winter/summer growth contrast look fairly good, even when rotary cut. I'm a bit picky about grain patterns, mostly because we have control over this. I'd prefer sliced veneers, which is what fine furniture is made from and understandably looks much better and costs more. When you epoxy up the planking, you'll see what you're going to get. Don't be so taken by the prettiness of the wet look that you forget about the grain.

[seanslife]

I'm still intending to use the Deks Olje #1 and #2 finish on my Tammie Norrie which is to be stored and used in a similar way to yours. There will be no epoxy coating because the oil will repel water (given the short and intermittent usage of 8-16 hours per month). I have a mate who has done exactly this on his Tammie Norrie and it looks great, has only annual maintenance and is easily touched up if there are knocks. have a look at the attached photo...
I intend to place a brass rubbing strip on the keel too, but I made the keel out of hardwood so I think it will survive fine anyway.
In my amateur and humble opinion it comes down to an assessment of the amount of boating I intend to do and what risks of saturation I am prepared to accept.

Sean