The "Building Bug" has bit me !!!! It's been a few years since I've really built anything. The last boat I built was a Hot Shot 45 about 4 years ago. I've mostly be into RTRs, and fibergalss hull kits, easy stuff. I've just about finished framing a 36''Dumas Eagle Hydro wood kit. I've replaced some of the wood with aircraft ply, and cut holes in the framing to lighten it up. My question is: Is there anything besides thinned epoxy to seal the inside with ?? Something new, easyer, cheaper, or LIGHTER ?? I plan to use thinned epoxy on the outside, but is fiberglass reinforcement really needed on the outside?? This will be just a play boat spending most of is time as a shelf queen, but I'd still like to build it the best, stongest, lightest way that I can. A good friend bought a built Dumas Miller American off of eBay, and this damn thing weighs a ton !! It's what I'm trying to avoid. Engine will be an OS 46. Any other tips, or suggestions are welcome. I've also been having a Miss Circus Circus (with fiberglass cowl), and a Miss Unlimited that I plan to build. Thanks for any input !!!

On the Miss circus circus I was told to stay away from it.The boat has serious build and weight issues. I was told to trace out the peices on to plywood and use the plywood to build your boat with. The Miss unlimited is the first boat that I will be building soon,but using plywood to build it with. Airplane plywood is what the boat guys are using to build there boats with.[8D]

Hi Rude777,

I built an Eagle. Be sure not to trap your fuel tanks under the deck. Make hatches on the bottom that you can screw and tape closed. Tanks always leak eventually, unless you go with all metal tanks and solder everything. Either that or locate your radio box in back and run a fuel tank up front where they show the radio box. I dont like that long push to the rudder anyways unless you go with a carbon fiber rod.

There's an old trick that doesn't hurt to use before you resin the inside of the hull so the resin doesn't sink in as much and stops you from using too much and that is to spray the inside good with a can of cheap hairspray. All it is, is laquer and pre-seals the wood and weighs nothing even if you use a whole can of it. Final Net is what I use. Just hose it when you spray it, not like your spray painting...point it up close and juice it.

What your trying to do is keep the epoxy on top of the wood, without hurting its ability to soak in a little. This is what the hair spray will do for you. It holds up just long enough to slow the rate of sink, without hampering the epoxy's abilty to soak and desolve past it into the wood until your long gone from the area, leaving you able to use just a thick enough coat to do the job.

I wouldn't glass the outside of it either. Glass can leave too much of a thickness and makes corners look like blobs, unless you really get into sanding and body fillers. Just use the good old K&B epoxy paint, or go with the new KlassKote epoxy and primers. I haven't tried it but that's next for me.

Another tip I'll suggest too building a Dumas kit is don't try and goop all the loose seams up with epoxy. Buy a couple of 1/8" strips of balsa and chop some glue blocks for all the joints. Wet the joint and the four blocks you'll need for every corner, and stick those in to dam up the epoxy to the joint. You'll get away from having to "web" such a large amount in the corners to make up for the huge joint gaps they have, and probably be much stronger besides. Looks ugly as sin before the decks are put on, but who cares after.

I have also been using a hot glue gun to scab some tack joints to hold everything in position exactly where I want it before I start going around to each seam with epoxy. When I get to a spot tack, I'll pick it off and glue that spot. It's a good idea to do only half the joints at first and let the epoxy cure, then go back and do the other half. Otherwise there's no point, and will move on you.

That hot glue comes in different heat ranges. Get the coldest stuff. You don't want to get the super hot stuff because you're not trying to make a permanent joint, and it will cook into the wood too good to pick off easy.

I also bought a cheap electric staple gun along with some short staples. If you practice your shots on some scrap joints first, you can get pretty accurate with it's aim, and be able to adjust how much hammer it has with its adjuster knob.

I used it putting on my curved decks on the Eagle and worked awesome. Lots better than trying to tape to wood. I left the staples a little high, so when the epoxy dried, I just gripped what I left sticking up with a pliers, and filled the marks with filler before I painted.

Here's some photos of mine. It's not completely painted yet, just pretty much two coats of epoxy paint and has let me see what the paint wasn't going to take care of, so there's still places I need to fill and sand, and the stuffing tube isn't installed yet which isn't a big deal to add before the last coat. I didnt want it in the way when I was leveling the bottom.

I got rid of the Dumas idea about the plastic flapper drain, and just made it a "wet" hull with drain holes and an open drain pan. Everything else was built like the directions, even including gluing in the tanks, big mistake..but oh whell...it was my first build before I started learning mistakes like that.

I removed 1/8" from the bottom of the air traps and replaced them with hardwood strips for wear protection and sharpness. Filling the open end-grained ply didn't thrill me as far as a quality outcome and durability.

I added brass inserts for solid machine threads for the turn fin bracket, radio box hold down blocks, and also for a brass bulkhead fitting for the water intlet to the transom.

Heres a couple shoots of my Eagle . You can see the pocket I made for the tanks . I also replaced the mahoganey with birch ply .

Ed.R

Hey Jetpack,
Thanks for the info !! Hair spray huh ? I'll try that. Your boat is lookin really good. Nice OPS. My OSs needle is in a funky position, I'll probably have make it a remote needle. What kind of hardware do you have in mind ? Prop ? Lifting prop? I've used KlassKote before, I love it. I'm working on my sponsons now. I'll post some pics when I get to a point to where I have something good to look at. I plan on shorting the nose, and making it alittle more square. Kinda like a top fuel drag hydro. Thanks again and please keep me posted on how it's going.

Hey Ed,
I like the tank pocket idea. I'll have to steal that one. Do you have hardware yet ? My biggest question is the rudder depth. 3" in the water enough? Nice lookin boat, that woodgrain looks really good with the blue. I tried to search "Dumas Eagle" on the web, but nothing came up. I was glad to see you and Jetpacks boats coming along so well. Thanks for the ideas. Keep me posted !!!!

I am not sure about this but I have never heard of using hairspray? I know most are using the slowest setting epoxy they can find so it will penetrate as much as possible. There are others on this forum that should click in on this suggestion, honestly it doesn't sound good but ya never know.


Paul

Hi Paul!

Rude777 is looking for a way to make his sealing job lighter. The goal is to not use slow set epoxy and let it sink into the wood as deep as possible. This is what adds excess weight. Hair spray is mostly laquer, and this is what forms the barrier coat which slows the speed inwhich the epoxy sets into the wood.

Hair spray has the advantage over pure laquer due to it being somewhat soluble when dry...that is what lets it wash out of people's hair. After the epoxy sits on top of the hair spray, and before it cures...it does have a chance to get past the hair spray and absorb into the pores like normal.

What you are trying to achive is to have the epoxy sit on top the wood as much as possible. It still is going to soak in, but the hair spray will impede that to an extent, so the quanity needed for it to roll out is less. It will have a tendency to stay on top longer so you are able to spread it out thinnner...it does not soak in deep as you are brushing.

This is also used by aircraft builders when they are fiberglassing over their wood. The goal is for the epoxy to skin the wood, not to saturate it. It still is going to adhere as strong as epoxy would.

If you ask around, you might be able to find an old timer thats been around it a lot that remembers this.

Rude777 about the hardware question you had for me, I have a combination of Speedmaster and CB Marine gear that I copy and machine myself.

The engine mount is Marine Specialties. Good stuff if you like lightness and dont mind cast, not machined. He caters mostly to the gas guys, but does some smaller nitro gear.

Okay, time for me to chime in on this one. I see some "questionable statements that I think need to be addressed:
1) NEVER USE BALSA IN A HYDROPLANE FOR STRUCTUAL PARTS!!!!!!!!!!! Balsa will not handle the pounding the hull will take. Notch the frames and install a solid SPRUCE stringer instead
2) HAIR SPRAY IS WATER SOLUBLE, DO NOT USE IT AS IT HAS WATER IN IT THAT WILL SOAK INTO THE WOOD Aircraft dope is a much better alternative as a lightweight sealer if weight is that much of a factor and epoxy isn't an option. Better still is that it's fuel proof
3) CUT LIGHTENING HOLES IN ALL UNDERDECK FRAMES, this will cut your boats weight by up to 40%
4) Build your boat from 1/16th ply with 1/4 ply transoms. You wil save another 35+% in weight
5) HOT GLUE??????????????????????????????????????????? NOT IN MY BUILDS, EVEN TO TACK. If I want to tack something, I'll use CA so there is no question about the part moving

the balsa is to hold the glue to the corners not for stringers. slow down and read. balsa is fine for using as glue filler blocks in corners to get away from using a large fillet of epoxy to close the joint for great weight savings without sacrificing strength. nobody mentioned it for structural building such as stringers.

hair spray such as final net does not contain "water" where it "soaks" the wood - it is fine as a barrier coat, and has been used sucessfully, cheaply and easily for years with laminators. You do NOT want to use airplane dope as a barrier coat. It does not dissolve under epoxy, and will peel off wood like a sheet of paper if water gets under it.

Rude already knows about the aircraft wood, hes already replaced some with aircraft ply to save weight.

when you use CA as a tack glue..i hope your tacks are perfectly in place the first time...you dont get another chance at gluing the joint over again, and your not bending and pressing on the wood to get it to kick off.

I would never use CA on ply that is eventually going to recieve epoxy. it is better to let the epoxy reach the wood, and not sit on top of CA that pipes itself a good inch away each side of the seam. You are starving the joint of epoxy. have you ever tested the strengh of epoxy over CA film? I have and it sucks.

A dab of hot glue for a small tack is perfectly acceptable and superior over CA for repositioning before it sets. If you sight or measure your layup and see that it is off, or you want to change something before you final glue the sheet or what have you, it gives you another chance and peels off very easy leaving the wood like you never touched it. Much better gap filling ability during tack work. It works great. It is POSITIONABLE and RE-POSITIONAL.

You dont have to be sorry about large gaps when building ever again, in fact...tight joints are not even really desirable due to their ability to spring and twist the entire framework when pulled off the jig. Hot glue tacks and balsa glue blocks. Best way to reach a perfectly straight, strong build. The worst framework is one that is built under joint tension. Float everything in, then "freeze" it with your balsa glue blocks in your wetted corner.

75% weight savings? Where's the boat?

I gave my opinion based on 25+ years of experience. Sorry if you don't like a tried and proven way of building. Not my fault if the hull fails, so forget I said anything and do it your way since I obviously dont' know anything about building a hydro

Hey guys we are only talking about a couple oz. of epoxy here if that is to much weight then maybe something else may be slowing the boats down like lack of power, wrong prop ect, if you are going to skimp on the stuff that holds your boat together it is time to find another way of saving weight.

Exactly !!

Aaaaaaaaaaanyway, thanks guys for your suggestions. Thank you Jetpack for some really creative ideas. I'll try some of them just for the hell of it. There's ALWAYS more than one way to do ANYTHING. Ya can't just do things because that's the way we have always done it. It's been a while sense I've had a build so I was wondering if there were anything new to try. New sealing products maybe?? I didn't mean to start a cat fight.

I can't say I have been building boats for 25+ years, but the tips I suggested at worse will not hurt anything if tried. It is all to the plus side.

The hairspray will dissolve and fuse with the epoxy as it sets. Once the epoxy has fused and cured itself with it and is in the wood, water has no effect on it.

The balsa glue blocks in the corner joints of the bulkheads or anywhere else you see fit can only be a benifit on making sure the epoxy stays where it should without having to build up a large fillet of epoxy in hopes to just to fill a gap. The fact that it is balsa doesn't matter. It could even be a creased slip of paper that gets pushed into the corner to do the job. All you're trying to do is dam up the epoxy and keep it in the joint.