new 222 rebuild

[JimCt]

My 240 had green gelcoat (brushed, mostly) all over the inside.  In many places it was covered over with subsequent layers of resin/roving.  No bond whatsoever.

Quick question, Shine, since you mentioned wood flour... is the purpose of the flour ease in sanding?  Easier than cabosil-filled resin?

[LilRichard]

So you're telling me if I bonded to the green stuff, I am FUBARed?

[JimCt]

If you sanded it thoroughly with coarse grit you should be OK.  In my case, Aquasport simply glassed over the smooth gelcoat.

My boat was full of surprises.  Hope I've found them all...

[John Jones]

Quick question, Shine, since you mentioned wood flour... is the purpose of the flour ease in sanding?  Easier than cabosil-filled resin?

Yep.  Not as strong as an adhesive nor structurally as strong but nice for filling holes, fairing corners, etc.  Sanding is much easier.  Leaves a tan patch.  I'm no expert but I wouldn't use it below the waterline.

[JimCt]

Will give it a shot.
  Sanding cabosil-filled resin in an inside 3-way corner is a bear!

[Shine]

Woodflour makes a very strong fillet mix and a very strong glue (with epoxy).  Woodflour glue is better than silica/cabosil its not brittle.  Adding just  a little silca/cabosil to the wood flour will make it smoother in consistency and less likely to sag.  The wood flour comes from an industrial wood products supplier and is super fine.  Its a little easier to sand, but I try to avoid sanding anything other than fairing compound.

I have the transom foam cut out, just need to trim it to shape.  Will post pictures soon.

Joel

[JimCt]

What fairing compound do you use?

[LilRichard]

Is it adviseable to use wood flour with Polyester resin?

[Shine]

We mix Phenolic Micro Balloons with a touch of silica to give a nice fairing mix.  I mix this with the same Marinepoxy for large fairing.  For the final fairing I use System Three Quick Fair - is fantastic/  Super smooth and can be sanded in 4 hours

Im sure you can use wood flour with polyester, but I have never done it.  I only use polyester to make full parts in one shot - then all secondary bonding is done with epoxy.

For this boat, i may use polyester to make some frames and stringers, then tape tab them to the hull with epoxy and biaxial tape.

We will see

[Shine]

August 4

Bedding the transom core.  The Transom core is Renicell E240 from DIAB, 2” thickness.  The foam will is bedded in epoxy glue made from regular Marinepoxy and woodflour/silica.  

The cardboard template was used to cut the core, then we dry fit it into the boat.  The core was trimmed so that it fit flush again the outside skin.  This of course leaves gaps around the sides that will be filled with epoxy before the inside glassing begins.  It is VERY important to avoid gaps between the core and the skins so make sure the core fits flush.  The idea in bedding your core is to apply even pressure all around to squeeze out excess epoxy glue.  Epoxy is a great gap filler.  Bonds are stronger when you do not squeeze out too much.  
We used galvanized bolts to pull the core into the skin.  The bolds are spaced  at 8”.  For a plywood core I would recommend more bolts (plywood is much stiffer).  Two of the bolts on the top/outside are facing inward, this gives a place to “hang” the glued core, while the other bolts are put through facing out.










Dry fit and do a test run!  We glued this transom (2 people) in less than 20 minutes from the first mixing of epoxy to the last tightening of the bolts.  On this day it was at least 90 degrees, so you will not have much time even with a SLOW hardener.  









We rolled a coat of unthickened epoxy onto the core and the inside skin before the glue was applied with the notched spreader.  Glue was applied to both the core and the skin. The core was “hung” on the skin.  Bolts were tightened beginning with the inside and working out.  Any material squeezed out was removed.

TIPS:  

Have multiple 1 quart mixing cups ready
One person does nothing but mix the other mixes and spreads.
Store the epoxy in a refrigerator for a few hours before mixing to give a couple extra minutes
Pour, don’t pump – pumping takes too long
Use a notched spreader – helps to apply the glue evenly and gives an escape for air

We mixed 5 pots of glue. Each pot was 15 oz of epoxy total (10 resin, 5 oz. hardener) and enough woodfour/silca to give us a nice non-sagging constancy.  I estimate we put 3 quarts of glue total down and squeezes out 1 pint.

[warthog5]

Now that you have the core in.

If you would have went ahead and cut the core 1/2in or 3/4in shorter than the outside skin, that would give you a shelf for the topcap to sit on. Depending on the thickness of the material used for the top cap.

Much easier to cut before it's installed. especiall if you are putting camber into the top cap. Which look's much better than a stright across transom.
It's hard to see in this pix.

[Tim/GA]

Only 90 degrees, must be nice to work in such cool weather!  I know what you mean about the slow hardner.  Pretty much been working in 95 plus weather this summer here near the coast in GA.  Been a killer!  Especially the grinding.  I have been very happy with the epoxy resin and slow hardner from US Composites.  Still has a very good pot life, even in this heat.

[Shine]

Im not sure how we are going to finish the transom; motorwell or flush with bracket. I am sure it will have a camber, just dont know how much a I want yet

I am leaning towards closing it in for a bracket.

Oh yeah, I took the melanine off yesterday.....

[warthog5]

A 1 1/2in rise in the middle look's good on them, for these width boat's.
It's not to radical and still easy to stand on.

But as I said, had you measured and layed it out with a batten and cut the core before you installed it life would have been much simpler.

http://www.classicmako.com/projects/xshark/bw4.htm

[Shine]

August 14, 2006

Put in first 2 layers of inside transom skin.  First layer is 1708, second is DB1700.  The inside skin will be 4 layers total of 17 oz. Biaxial glass.  The first layer has mat (1708) because the mat helps conform to any uneven spots in the fillet.  Subsequent layers will not have mat as it will just use more epoxy and not add strength.

I worked “wet on wet” for the fillets and the first two layers of glass.  Using a mix of silica/woodflour and epoxy, the gaps along the sides and bottom of the core had been filled so the filler was level with the core.   Using the same mix, we laid fillets along the joint.  This fillet is about ½” radius.





After 15 minutes or so, the fillet is firm but not hard.  At this point we lay in the pre-wet 1708.  Because the fillet is not hard, you will be able to push the glass into the fillet making for a very clean lamination – no air bubbles.  A second layer of DB1700 was wet out on top of the 1708.  DB1700 (17 oz. with out mat) wets out much easier than 1708, so you can do it on the part – no need to wet out the back side before placing it.





All the inside layers will be overlapped by 3”-4” working up the hull.   Working wet on wet saves time and makes for better laminations.   In this case we should have gone ahead with the last 2 layers, but time did not permit.

Joel