Boat Builder Central - Builder Forums

I bought a mold for a 16' McKenzie style drift boat. Previous owner built boats with polyester resin but I've been reading that epoxy is the way to go. What I'm not sure of is do I apply a gel coat first, then glass, then epoxy on the inside? Or do I just lay the glass down and epoxy over that then pull it out after full cure then gel coat the outside? He also said one thick layer of biaxial glass is strong enough to hold. The design does have large storage bins and two benches which will help as cross-supports but one layer of glass has me a little nervous. I'm going to do a practice cross-section but wondering what the 'normal' thickness should be. Any help is greatly appreciated!

JM will have a expert opinion, but anyone who has seen an all fiberglass boat cut up knows that it is very think, and not 1 layer. Without the wood providing support, you need lots of glass for structure. When I have watched boats being made in this manor (there are some good videos online) they have always sprayed in the polyester, I'm not sure how this could be accomplished with epoxy. They also tend to use lots of chop strand type stuff and mat, so maybe what he was saying is that it only needs one layer of BA cloth, but then lots of the others? I would definitely get some expert advice on this before proceeding to far.

Ditto what AMC said. a long time ago out west I worked in glass shops and these type of boats have at least 70 oz gloth, heavy woven roving and chop back in the day. There are better ways to do it now with material like 1708 and the triaxials and even quadaxials, you could even do carbon fibre if you wanted light weight but on a drift boat light means you get blown around a lot more/have to paddle against the wind more. I would pay JM for a layup schedule.

As far as gel coat that is just pigmented resin but, I don't think you can spray epoxy. I made a female mold for the deck of my PH18 and just did the layup per JM's notes. One word of caution - be sure you have enough resin on the mold surface - I laid up the cloth without wetting the mold surface and I have 2 million + tiny little air bubbles on the surface. No big deal just a lot of primer and sanding. Also, look into the Frecote brand of silicone based mold release compounds - new age technology, outstanding release. My entire deck just popped off with a shots of air in between the part and the mold.

These boats are the cat's meow for fly fishing on rivers - I made many trips on them down the Bow River in Calgary throughout the '80's and early '90's....

One clarification - it was recommended to me to put a 1/2" layer of lightweight bass wood on the floor which is glassed in and a 4" strip around the gunwale. One thing I haven't seen as well is the proper way to anchor knee braces to the floor. Anybody have reference information for that? I'm concerned with the strength of the floor holding the braces solid. I appreciate the information on getting a layup schedule, etc. Many thanks!

Drift boat plans came up a long time ago. jacques bulked at the idea because he didn't have any first hand knowledge of them.Still don't know if he does.
The mold process you are talking about. first off when useing epoxy you don't need gel coat. Gel coat is a water proofing for hulls that use polyester resin. Water seeps through polyester. epoxy NADA. With a drift boat i would reccomend useing epoxy/graphite mix for hull bottom. the rest just fair, sand and paint like the rest of boats being built.If you have a mold, waxs the hell out of it witrh mold release wax. Time wise with the heat the way it is you would have to have a pretty air conditioned very cool atmosphere to work with. Uou need some fast working to beat the epoxy from kicking off. Two totally dif working times between the two resins. I would really think it out before I went with epoxy. This stuff is great but can be really messy when it starts to kick off. Better have some experience behind you and make sure you have some extra help. One to mix while the others help to lay out the cloth and start wetting it out. Not an easy task. The epoxy/ graphit is added after the hull is removed from a mold. I may be wrong on some of this , but I do know you can get into trouble if you don't have all your eggs in a basket so to speak.

Thanks Sticky! Wasn't sure on the gel coat with epoxy. So do you let it cure up then pull the mold, flip over, sand and paint the outside? I've done epoxy flooring so I'm familiar with the working times of epoxy. Total greenhorn on boat-building though! I'm planning on making all the seats, etc in the summer then glassing them in on the final assembly day in the fall when it's cooler so I do have more working time. The plan is to have all the glass cut out and layer out in order so we're not fumbling around with that. Also hoping to have a few helpers as well like you say.

i can't honestly give you a correct answer on the mold part. I made some small hatch molds and waxed the crap out of them The epoxied parts came off very easy. As far as a full size mold like you are talking about i see no reason it wont come off. just wax the crap out of the mold. Sometimes it takes air pressure to pop a part out of a mold. All i can say is experiment.

Moved to the repair section.