91 chawk 222 rebuild

Questions about boat repairs with our resins and fiberglass: hull patches, transoms and stringers, foam, rot etc.
fallguy1000
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Re: 91 chawk 222 rebuild

Post by fallguy1000 »

Stinkbait wrote: Sun Oct 11, 2020 8:32 pm at least i have a couple pics up, my original plan was to replace any material that is removed w coosa and was impressed from what ive read up on it, but i really cant see spending $380 a sheet at a min of 8 sheets total for a commercial grade hull for the chesapeake. my local lumber yard has 3/4 inch marine ply for 108 a sheet and 90 for 1/2 inch. from what ive seen so far, it looks like all the structure is lined w either single or double 3/4 board,so im just gonna put it the same material i take out. it lasted almost 30 years, if i can get half that im happy. i hit the transom pretty good today, just have the corners left where cap meets. was thinking of trying to unscrew the capabout 1/3 of the up and try to lightly flex up and brace w 2x4s so i can work. anyone ever attempt this or am i crazy?.
It might be doable. But make sure you don't lose the shape when you lift the cap.
My boat build is here -------->

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LilRichard
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Re: 91 chawk 222 rebuild

Post by LilRichard »

Stinkbait wrote: Sun Oct 11, 2020 8:32 pm at least i have a couple pics up, my original plan was to replace any material that is removed w coosa and was impressed from what ive read up on it, but i really cant see spending $380 a sheet at a min of 8 sheets total for a commercial grade hull for the chesapeake. my local lumber yard has 3/4 inch marine ply for 108 a sheet and 90 for 1/2 inch. from what ive seen so far, it looks like all the structure is lined w either single or double 3/4 board,so im just gonna put it the same material i take out. it lasted almost 30 years, if i can get half that im happy. i hit the transom pretty good today, just have the corners left where cap meets. was thinking of trying to unscrew the capabout 1/3 of the up and try to lightly flex up and brace w 2x4s so i can work. anyone ever attempt this or am i crazy?.
Neat build. I grew up fishing on a friend's 25' C-Hawk, it is a great boat.

if you were considering going composite anywhere, I would suggest Coosa for the transom. I agree marine ply is fine for the other cores, just be sure to overdrill and backfill all penetrations (to avoid future water intrusion).

If you end up re-stringing the entire hull, I might consider a 4 pound foam for those, either using sheets cut to shape/fit then glassed over, or building a stringer mold, then backfilling with pour-foam. I'd prefer not to do stringers on a boat twice. Here are pics of foam sheet being cut to size, then glassed over:

Image

Image

Note that I marked each piece of glass prior to lamination, so I knew where it went (both layer #, and top corners)... that helps a lot when racing against the resin clock.

fallguy1000
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Re: 91 chawk 222 rebuild

Post by fallguy1000 »

LilRichard wrote: Mon Oct 12, 2020 9:47 am
Stinkbait wrote: Sun Oct 11, 2020 8:32 pm at least i have a couple pics up, my original plan was to replace any material that is removed w coosa and was impressed from what ive read up on it, but i really cant see spending $380 a sheet at a min of 8 sheets total for a commercial grade hull for the chesapeake. my local lumber yard has 3/4 inch marine ply for 108 a sheet and 90 for 1/2 inch. from what ive seen so far, it looks like all the structure is lined w either single or double 3/4 board,so im just gonna put it the same material i take out. it lasted almost 30 years, if i can get half that im happy. i hit the transom pretty good today, just have the corners left where cap meets. was thinking of trying to unscrew the capabout 1/3 of the up and try to lightly flex up and brace w 2x4s so i can work. anyone ever attempt this or am i crazy?.
Neat build. I grew up fishing on a friend's 25' C-Hawk, it is a great boat.

if you were considering going composite anywhere, I would suggest Coosa for the transom. I agree marine ply is fine for the other cores, just be sure to overdrill and backfill all penetrations (to avoid future water intrusion).

If you end up re-stringing the entire hull, I might consider a 4 pound foam for those, either using sheets cut to shape/fit then glassed over, or building a stringer mold, then backfilling with pour-foam. I'd prefer not to do stringers on a boat twice. Here are pics of foam sheet being cut to size, then glassed over:

Image

Image

Note that I marked each piece of glass prior to lamination, so I knew where it went (both layer #, and top corners)... that helps a lot when racing against the resin clock.
Good post. Note that 4# foam does not replace a timber stringer. You must come back with more glass and epoxy vs esters. On balance, I agree very much. Consider in 15 years not giving a damn about rotten stringers or transom. Yes, coosa is costly, but your materials can be high if you are doing all the labor inputs.
My boat build is here -------->

viewtopic.php?f=12&t=62495

Stinkbait
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Re: 91 chawk 222 rebuild

Post by Stinkbait »

I like the idea of that foam, the 2 inner stringer are 1.5 thick(double 3/4" ply ) the two outers are single 3/4, to this point I've only removed the floor over the tank and about 4 ft forward of stern. I wanted to try to keep as much structure in place since this is gonna be a very slow project due to work schedule and winter is right around the corner. Im hoping to atleast have the transom completed before the cold sets in. I plan on now using marine epoxy and the recommended medium hardener , what the coolest temp this stuff is workable and what temp does it need to kick? It can get 70s in the day and drop into the 40s at night, is that to cold?After that I'm gonna remove the floor up to the most forward bulkhead to inspect all stringers and remove/replace/or repair one at a time. Sound like a good strategy? If they have to come completely out I just may go w the foam gotta be a significant weight savings. For the transom I'm gonna over bore all holes and backfill w thickened epoxy, will wood flour and 1/4" chopped glass be a strong enough filler for those holes? Can I get away w glueing directly to that our should I laminate a layer of 1708? If so , mat or woven facing stern prior the glueing and clamping? Sur u can tell I'm a complete newbie, but definitely willing to learn. Thanks again. MIKE V

cracked_ribs
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Re: 91 chawk 222 rebuild

Post by cracked_ribs »

In the 70s it'll kick, but you will probably find it takes days to really harden. Overnight it will do nothing, and the material will cool down as well so unless you can get it in direct sunlight it'll only have a few hours during the day in which it makes the minimum temperature to activate. What usually takes 24 consecutive hours, now takes 24 hours, 4 hours per day. You will repeatedly question whether you screwed up a batch because the epoxy will be basically hard but with a rubbery feeling surface, but in my experience, no, it's just taking forever.

This can be an advantage - I like it until the last coat before paint, at which point I'm usually furious and pointing hair dryers and space heaters at it.

If you have the ability to heat up a garage or something you'll be glad you do. It's the cooling of the substrate that really slows everything down; you can get the epoxy up to temperature easily but spread out thin on a sheet that spends 75% of its time well below epoxy temperatures slows things to a crawl. Nice for laminating, though. It usually kicks well enough on day one and you can keep layering on other stuff for days afterwards, getting a perfect chemical bond.
I designed my own boat. This is the build thread:

viewtopic.php?f=12&t=65349

Fuzz
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Re: 91 chawk 222 rebuild

Post by Fuzz »

Wood flour and 1/4 glass will make a real strong filler. You should have no problems using it that way.
For your epoxy you might want to order a gallon of fast hardner. You can blend it with the medium if it is too fast for you. As stated there is both an upside and a down side to slow setting epoxy. Always good to have options :wink:
Between the transom glass and the core I would just make wood flour puddy and skip the 1708 unless you are needing more glass in the outside skin.

fallguy1000
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Re: 91 chawk 222 rebuild

Post by fallguy1000 »

Stinkbait wrote: Tue Oct 13, 2020 9:54 pm I like the idea of that foam, the 2 inner stringer are 1.5 thick(double 3/4" ply ) the two outers are single 3/4, to this point I've only removed the floor over the tank and about 4 ft forward of stern. I wanted to try to keep as much structure in place since this is gonna be a very slow project due to work schedule and winter is right around the corner. Im hoping to atleast have the transom completed before the cold sets in. I plan on now using marine epoxy and the recommended medium hardener , what the coolest temp this stuff is workable and what temp does it need to kick? It can get 70s in the day and drop into the 40s at night, is that to cold?After that I'm gonna remove the floor up to the most forward bulkhead to inspect all stringers and remove/replace/or repair one at a time. Sound like a good strategy? If they have to come completely out I just may go w the foam gotta be a significant weight savings. For the transom I'm gonna over bore all holes and backfill w thickened epoxy, will wood flour and 1/4" chopped glass be a strong enough filler for those holes? Can I get away w glueing directly to that our should I laminate a layer of 1708? If so , mat or woven facing stern prior the glueing and clamping? Sur u can tell I'm a complete newbie, but definitely willing to learn. Thanks again. MIKE V
Epoxy will cure at 70F just fine. But it needs about 16 hours at that temp.

If you are getting too cool overnite; it will not cure fully. A piece of tarp that won't settle down onto a heater can work. Just keep in mind the heater can warm the plastic covering or it can move in the wind. Best to put some planks under and over or tapes or ratchet straps, etc.
My boat build is here -------->

viewtopic.php?f=12&t=62495

Stinkbait
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Re: 91 chawk 222 rebuild

Post by Stinkbait »

Spent 8 hrs grinding today, might end up buying a 7 inch to speed things up. That whooped my tail today. Have outer core and 15 " up the sides and around the keel clean and solid glass. Decided to remove an old thru keel transducer(2 inch hole) , so I could get a cleaner glass layout on the center rear stringer, now I gotta read up on patching w bevel. Seems pretty straight forward FROM THE VIDS IVE SEENOrdered all my material as well. Decided I'm just gonna cut strips of the 1708 for the taping. Sound like a good idea/ structurally doable? Or should I get some 12 oz. Tape.? And to simplify things since I'm a newbie, can I just use 1708 for all the structurable things(stringers, bulkheads, tabbing/taping etc?) for the stringers, is it possible for me to sister the above foam board to existing double 3/4 ply then wrap it in multi 1708 or should I just stick w what was original and go back w ply? To keep it simple. Will try to get some pics up, I suck at it,but know it makes all the difference for advice.THANKS, MIKE V

fallguy1000
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Re: 91 chawk 222 rebuild

Post by fallguy1000 »

I do almost all structural tabbing with 1708 tapes.
My boat build is here -------->

viewtopic.php?f=12&t=62495

Stinkbait
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Re: 91 chawk 222 rebuild

Post by Stinkbait »

While I'm slacking on the pics, I've been cracking along. I have the transom ply set. Used the double 2 x 4 ,thru bolt and shims w clamps along the edges. And it turned out great imo. I also put the epoxy n hardener in the fridge to give me alil more time, since this is my first go at it,(not sure if I even made a difference. I was able to get it all spread and clamped with in 10 15 mins, and squeezed just enough to start seeing the peanut butter start to ooze out evenly from the 12 dozen or so holes in the outer skin and let her sit. I used the wood flour filets, and was pretty happy w the results, probably gonna stick them for all the structural stuff underneath deck. Tabbed in w 1708, did 4 layers at 6,10,12,14". I couldnt back to working on boat til today and its fully cured. I'm gonna spend today shaping the cap for glass, and prepping for the transom skin.(4layers of 1708)just to get back to what factory was, just shy of 1/4 inch. Should I just hit the tape w 80grit on a palm sander to scuff, or should I pull out the grinder and lightly scuff w that. Also I've read to clean all w water to remove amine , but I've also read use acetone, which one is best to get it to stick? Should I wrap my 1708 over the cap, or just comeback and cap it later, and since I've tabbed, pretty heavy imo, should I run transom sk in ns out to side hull overlapping or just build up the transom itself?, Thanks Mike V.

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