WATERPROOFING MY SCALE HYDRO

[mark couty]

I am wanting to find out how to waterproof my scale hydro, the OUTSIDE SKIN, and want to know how guys are doing this. I also want to know if I can spray the wood with automotive urethane clear and get the same result , as I am pretty handy with a spray gun. Let me know whats the most efficient way to do this. Thanks Guys.

 

[Dan Kramer]

I am wanting to find out how to waterproof my scale hydro, the OUTSIDE SKIN, and want to know how guys are doing this. I also want to know if I can spray the wood with automotive urethane clear and get the same result , as I am pretty handy with a spray gun. Let me know whats the most efficient way to do this. Thanks Guys.

i always west system (or similar product)the insde REAL good.

then when doing the final top sheeting, i do the complete UNDERSIDE and let set up.

next i cote the outside, let it set up, then blade the outside smooth.

paint systems then follow.

i would note recomend the paint system as a wood sealer.

 

[Hydro Junkie]

I have to agree, you need to seal the wood before you apply primer. Like Dan, I use West Systems, the 105 resin and, in my case, the 207 hardener. Apply it thin, finish sand and prime. I tried to just paint my first boat, a Dumas Pay'N Pak. The paint easily peeled off after a few weeks as anyplace there was a scratch water was able to get to the wood and expand the grain.

 

[Bill Gibson]

Im gonna 3rd it!!! West systems or similar thin epoxy EVERYWHERE on the boat...i like to use Dupont Corlar 2 part primer after sealing the wood also...

 

[Dan Kramer]

let me expand on this a little.

IF you use a primer , 2 part catalyzed only.

IF you dont need primer, such as in flawless woodworking,dont use it.

2 coats of west system(or similar),

completely sand or blade 1st coat, fix any imperfections in woodworking that may be there.

apply a 2nd coat.when dry, lightly sand nibs and scotch bright(purple pad)the entire surface completly, try not to break thru to wood. if you do, spot apply epoxy again.repeat sanding steps.

clean with mild soap and water, rinse completely and dry.

you can now paint the hull.

i have done many this way with excellent results.

 

[Kez]

Has anyone found it necessary to fiberglass the entire hull with light wt cloth? I have built many sport hydros of all sizes over the years using epoxy only to seal the hull. Hairline cracks in the high stress areas alway develop after one season or sooner. Typlically, I notice the sponson riding surfaces, tunnel floor beneath the engine mount, deck to non-trip joint and the non trip itself are all prone to stress cracks.

Once the hairline cracks started, it is a lot of work to repair the area. I use thin CA to reseal the crack until the offseason when I strip the paint to repair it.

I have since started glassing the high stress area but will try to glass the entire boat on my next build.

Just want to see if I am the only one with the problem.

kez

 

[Dasboatman]

Hey Kez,

I build Sport and Scale boats using Wood Over Foam (WOF) - usually Styrofoam sponsons and forward tub, white foam (2#/cu. ft.) aft to save some weight. I have always used 1/2 to 1 oz. cloth with epoxy resin forward of the firewall for structural strength and add weight forward (pic attached) - - I hate to use lead to balance to C/G.

If you are building framed hulls, I would think the glass cloth would almost be a necessity to keep the seams together - just keep the afterplane as light as you can. CHEERS !!! Bob

 

[Kez]

Hey Kez,

I build Sport and Scale boats using Wood Over Foam (WOF) - usually Styrofoam sponsons and forward tub, white foam (2#/cu. ft.) aft to save some weight. I have always used 1/2 to 1 oz. cloth with epoxy resin forward of the firewall for structural strength and add weight forward (pic attached) - - I hate to use lead to balance to C/G.

If you are building framed hulls, I would think the glass cloth would almost be a necessity to keep the seams together - just keep the afterplane as light as you can. CHEERS !!! Bob

Nice build there Bob! Was it from a Newton's plan?

With the WOF construction, the ply skin is supported unlike a build up frame where the skin is not supported between frames. I started glassing the seams many years ago and the weak link is now the ply skin. Typically, the ply between frames can flex and the result is hiarline cracks. It is noticeable as the water seeps into the crack and rasie the wood grain. Eventually the area will become oil soaked. So I now glass the entire hull with 0.6 oz cloth with west system.

Thanks,

kez

 

[Dasboatman]

"Nice build there Bob! Was it from a Newton's plan?"

Thank you Kez. No, they are hulls of my own design. I only use the Newton paint plan as a starting point, for overall dimensions, graphics and cowl shape - all the angles are my own.

I have built a few framed hulls over the years and have seen the same issues you describe. Hence the reason I build WOF. When finished a WOF hull is very strong - you could just about stand on the hulls with rudder and turn fin removed. And they are very easy to repair after one gets hit or driven over.

The hull in previous pic is actually the 'Twin' of a second hull. Big difference is that Rick finished his a few years ago - I'm still letting the epoxy cure on mine- Har, Har !!! CHEERS !!! Bob

 

[misshydro]

let me expand on this a little.

IF you use a primer , 2 part catalyzed only.

IF you dont need primer, such as in flawless woodworking,dont use it.

2 coats of west system(or similar),

completely sand or blade 1st coat, fix any imperfections in woodworking that may be there.

apply a 2nd coat.when dry, lightly sand nibs and scotch bright(purple pad)the entire surface completly, try not to break thru to wood. if you do, spot apply epoxy again.repeat sanding steps.

clean with mild soap and water, rinse completely and dry.

you can now paint the hull.

i have done many this way with excellent results.

ok Dan. You tought me and joe to apply one coat of epoxy/west system or aeromarine or another marine epoxys then blade it and scotchbright the edges. Then put one coat of clear,then paint it.But if your going for the woodlooks then apply 2 coats of clear. the proublem in just clearing it is. One you have to apply many of coats of clear because the wood soaks it in so much=adding weight. By applying acoat of epoxy is that it will soaks in the wood.But not as much as clears does.But the epoxy adds strength to the skins.We're doing this prosses on the JAE.12 rigger that are very touchy in weight factor.

 

[Duck899]

I am wanting to find out how to waterproof my scale hydro, the OUTSIDE SKIN, and want to know how guys are doing this. I also want to know if I can spray the wood with automotive urethane clear and get the same result , as I am pretty handy with a spray gun. Let me know whats the most efficient way to do this. Thanks Guys.

West sytems is the only way to go. It sands very nice. You might even have to do it twice to get the surface smooth. Then primer (spray) all coats from there. Sand the primer and fill all the low spots and imperfections and keep the corners sharp on the bottom. When satisfied, spray white for the base and again check for blemishes and sand and keep corners sharp. Now your ready for color.....sand after painting...keeping corners sharp on the bottom and apply or paint decals, then clear. I use dupont chromaclear and sand with 2000 grit wet/dry and buff with a power polisher using Meguires polishing compound and then carnauba wax.

 

[Hydro Junkie]

Bob and Kez, I have to disagree on the requirement of glassing an entire hull. Glassing the entire hull has two serious drawbacks:

1) If the hull is damaged in one area, it's considerably harder to make a repair without damaging other areas of the hull that weren't damaged initially. If the repair requires feathering of the edges to get a smooth face for a seamless repainting, now you have to feather sand through old paint, epoxy/polyester resin AND GLASS

2) We all know that a lighter boat will accelerate quicker, is easier on hardware and requires less engine power to get that acceleration. Even using the .5, .6 or .75 glass will still add around a pound of weight, MINIMUM, between the weight of the glass and the resin required to fill the fabric weave. That extra weight can cause handling problems by flexing the skid fin or rudder, not to mention requiring a boat to run a lifting prop when it may not have needed to without the addition of the glass coating. It is my opinion that the added weight is an unneeded extravigance or an admission by a builder that they don't trust their ablility to build a wood over frame hull.

If a wood over frame boat is properly built, there is no reason for the skin to flex over the framing. This is one of the reasons I won't build a boat with CA and then coat the joints with epoxy after the fact. Epoxy won't penetrate a joint that is held together by CA, so those joints will, in my opinion, always be suseptible to failing due to the brittle nature of CA

 

[mark couty]

OK you guys, I'm a rookie here, someone tell me what "BLADING" is.

 

[Hydro Junkie]

Blading is a process where you coat the hull with epoxy and let it start to set up. You then take a scraper and remove most of the excess epoxy off the hull, leaving a very thin layer of resin on the hull and in the hull's surface

 

[misshydro]

(hydrojunkie quotes)..If a wood over frame boat is properly built, there is no reason for the skin to flex over the framing. This is one of the reasons I won't build a boat with CA and then coat the joints with epoxy after the fact. Epoxy won't penetrate a joint that is held together by CA, so those joints will, in my opinion, always be suseptible to failing due to the brittle nature of CA .......CA pentrates deeper into the wood then epoxy. Some reson why they crack is CA wont flex and epoxy will flex. Oh HJ it also depend on what CA your using too.. Theres a flexable version out as what I was told.

 

[Dan Kramer]

OK you guys, I'm a rookie here, someone tell me what "BLADING" is.

i use a single edge razor blade, grip it between thumb and finger , gently scrape it across the surface. blade will be 90' to the surface. with a little practice you can do this very quickly.

 

[mark couty]

Miss Hydro, I value everyones opinion and its good to see a lady boater. You sound pretty knowledgeable in the construction area, how many boats have you built ? How many scale hydros have you built ? I am currently building a 1/8 scale 1982 Atlas Van Lines Hydro. I am asking questions as I go and also for future reference. Can you recommend a good prop for this boat ? I will be using a K&B .67, 11cc.

 

[Hydro Junkie]

Misshydro, I've also heard of a flexible CA, but since the flexible CA is partially acrylic, which is not flexible, I still wouldn't trust it for a structural joint in a boat build. Now if you want to try it and report back to the rest of us, go for it.

 

[mark couty]

(hydrojunkie quotes)..If a wood over frame boat is properly built, there is no reason for the skin to flex over the framing. This is one of the reasons I won't build a boat with CA and then coat the joints with epoxy after the fact. Epoxy won't penetrate a joint that is held together by CA, so those joints will, in my opinion, always be suseptible to failing due to the brittle nature of CA .......CA pentrates deeper into the wood then epoxy. Some reson why they crack is CA wont flex and epoxy will flex. Oh HJ it also depend on what CA your using too.. Theres a flexable version out as what I was told.

Thanks to all for the replys and to you Miss Hydro, good to see a lady boater. You sound knowledgeable in construction. How many wood boats have you built ? How many scale hydros have you built ? I am currecntly building a 1/8 scale 1982 Atlas Van Lines Hydro. Could you recommend a good prop for this boat, I am using the K&B 11cc, .67 inboard.

 

[misshydro]

(hydrojunkie quotes)..If a wood over frame boat is properly built, there is no reason for the skin to flex over the framing. This is one of the reasons I won't build a boat with CA and then coat the joints with epoxy after the fact. Epoxy won't penetrate a joint that is held together by CA, so those joints will, in my opinion, always be suseptible to failing due to the brittle nature of CA .......CA pentrates deeper into the wood then epoxy. Some reson why they crack is CA wont flex and epoxy will flex. Oh HJ it also depend on what CA your using too.. Theres a flexable version out as what I was told.

Thanks to all for the replys and to you Miss Hydro, good to see a lady boater. You sound knowledgeable in construction. How many wood boats have you built ? How many scale hydros have you built ? I am currecntly building a 1/8 scale 1982 Atlas Van Lines Hydro. Could you recommend a good prop for this boat, I am using the K&B 11cc, .67 inboard.

Built 4.. 2 JAE's 1 dumas eagel and 1 ten foot round nose hydro in highschool... Got a 82 atlas style hull I'm building now. Joe=hubby got some good friends that can really build boats.. One just posted on hear,Dan Kramer. We learn alot from guys like him and Rick Reighsinger,Ron Olson and Rod Garaghty and Phil Thomas..