Divinycell vs balsa core

[LOSTINJ]

I restoring a vegas xt and of course the core is history . There was a thread years back on how thin these boats are and I get it as they were on the built cheap and by 5.00 hour labor . I removed all rotted balsa and plan to roll in two layers of 1708 to toughen it up then core , orig core was 3/8 balsa and balsa is what I've always used , however I have 35 years exp and a buddy with much more exp was informing me the benefits of H-80 Divinycell of balsa . It softens the impacts over balsa with low water absorption. I just read the Swedish royal navy used Divinycell for core below water line along with Vinylester resin for the same reason . I also only use Vinylester resin .
Question is I removed 3/8 balsa and do I use 3/8 H-80 Divinycell in its place and have the same strength ? When you look at the Lab data specs on balsa VS Divinycell , Balsa Excels in almost every test

[Da Bull]

Hard to beat Balsa if done right. When Mr Summerford owned Laser Boats then later STV he used Klegecell in the bottom. Can`t beat experience where time after time in hundreds of hulls on rough race courses. My Laser 380 is a 1982 with Klegecell/Kevlar layup and it`s still strong. Balsa is good but not the only way to go.

[loop]

curious about why youre adding 2 layers of 1708.
EDIT sorry I didnt see the part about toughening it up. That makes sense

[LOSTINJ]

I've always use balsa and its clear to see why the core fails on these boats , only covering with layer of roving and resin falls thru some of the squares and all it would have taken was layer of 1.5 over roven . Building boats for local company in the 80's I get it , it was just get it dine and out the door . Well after core is removed the bottom is paper thin as when you walk on it flexes and that's before I grind it . Installing new transom with knees with marine plywood , deleting splash well . Having custom alum 40 gal vee belly tank made , using Coosa 26 for floor . Running a 15 inch 300x copy so its more power than I really need

[XstreamVking]

Use the 1/2'' -80 d-cell to replace the 3/8 balsa.....Do not bond the d-cell with vinylester. Use some bedding compound. It is usually ortho resin or iso resin and works better.

[JPEROG]

Balsa won't handle anywhere near the number of blow cycles that a quality closed cell foam core will before it turns to powder. I have learned a lot from watching and being around Doug Wright and Scott Porta in the last 7 years. There is no reason to gamble with balsa core.

Joe

[LOSTINJ]

Exactly what I have learned that the foam will absorb the shock load rather stiff as brick with Balsa . Please inform about bedding compound as when we used balsa it would get pushed into resin rich chopped mat . I only use Vinylester resin

[XstreamVking]

Core bond or divilette bedding compound will work well. Edit....Also coosa 26# is overkill for the floor, the 1/2'' 12# is all that is needed. One layer of 1.5 oz matt under, one layer 1.5 oz on top and tab in around the perimeter with 1708 covered in 1.5 oz matt is what i did with the floor in my v-king. Has held up for many years. 3/4'' 26# for transom and knees's is what I used. That has held up great also.

[LOSTINJ]

Noted, I assume you meant 15LB coosa ? . Also this Vegas 20 XT and im assuming no hydrostream had stingers or bulkhead's. So I'm going to add 2 one in front of fuel tank and the other aft of tank .
Also any tips on the bedding of the core ? I assume over cured 1.5 mat ?

[XstreamVking]

Over fresh cured and lightly ground mat is good. Apply approx 3/16''-1/4'' bedding on core and hull portioned equally on each.. Apply enough pressure to get some to squeeze out the edges and spaces between the scrim squares. Some additional vent holes help too. Dry paint roller and laminating rollers work well to apply pressure to the core. Light weights on curved areas will help keep it placed. Flat areas will usually stay put. Vac bagging is best if you have the equipment. Always read the instructions for the product you are using for best tech. info.

[LOSTINJ]

Thx . Will 5 gal pail do the core in this vegas core only 3 ft wide x 12ft or so

[XstreamVking]

Should do it....

[LOSTINJ]

I forgot to point out very important point first off these hydrostreams are built paper thin as anyone who ripped a core out can tell you , that said the single most important part of recore has to be proper support of the hull while performing recore . This support is also crucial for an intact boat as mentioned these are paper thin and combined with wet core on bunk trailer it severely warped the bottom . I have the Vegas XT blocked up on hard outer part of bottom to let the bottom kind of find its orig position. Im sure this cant be the only one where besides the trailer bunks pushed up bottom combined with wet core the boat has severe hook in it . I have an auto rotisserie which as soon as I make a fixture to attach I will be rolling boat over to evaluate the bottom
After the boat is done I will be reworking the bunk arraignment to keep bottom straight . IT is most important that the bunks come out past bottom boat , if not your warping the bottom , this trailer bunk stopped short around 4 inches which severely added to the bottom being deflected upward from being thin and wet core

[XstreamVking]

Just don't let it get rocker. You won't be able to drive it with a bowed bottom. Make it as straight as you can and watch out for any twist. When recore is done, flip it over and do a blueprint job on the last 8'. Sharpen the strakes and all trailing edges.

[LOSTINJ]

Yup