23 Sceptre - last unmolested one

[FishStretcher]

As an idea:

3 layers of 10mm/0.394" garolite for a core under the I/O cutout. The middle layer thicker, like lettuce hanging out of a BLT. Maybe CSM in between to make the stack 1.375" That allows a gradual stiffness change away from the I/O cutout, but generally the bigger garolite pieces, the better. Then coosa everywhere else. Kind of a pain to construct, but It gets compressive stiffness and strength where you need it. And attemts to manage a stiffness transition.

If it wasn't so expensive, I would push the garolite out to the first step in the hull.

[FLexpat]

Originally Posted by FishStretcher

As an idea:

3 layers of 10mm/0.394" garolite for a core under the I/O cutout. The middle layer thicker, like lettuce hanging out of a BLT. Maybe CSM in between to make the stack 1.375" That allows a gradual stiffness change away from the I/O cutout, but generally the bigger garolite pieces, the better. Then coosa everywhere else. Kind of a pain to construct, but It gets compressive stiffness and strength where you need it. And attemts to manage a stiffness transition.

If it wasn't so expensive, I would push the garolite out to the first step in the hull.

I like it! My tooling will limit me though; I probably have to reverse what I think you are saying with the outer layers wider and taller than the middle layer and forward layers. the smallest layer would be in the middle of the sandwich. I tried to show it in this pdf.
Garolite Drive plug v2.pdf
I'm thinking the largest layer goes outside or aft - I don't want any of the edges lining up. This gets the garolite about half way to the first step from the centerline and the entire transom housing surface and bolts are backed by garolite.

[FLexpat]

Haven’t been able to get much done except cut a template for the transom core. I used a sheet of pegboard and used screws in a couple of holes in it that lined up with holes in the transom skin to hold it in place while I marked it. I am also going to use it as a template for drilling a bunch of bleeder holes through the core before I do the layup.



I am trying to decide on the best filler to go between the edges of the core and the hull. I think I will have to fill about 1/8”-3/16” all the way around the core. My intention is to do all the glass/epoxy layup and filler at the same time when I vacuum bag the core into place. I know I will be under a time crunch during the layup since I’m adding 2 layers of glass between the core and the exterior skin, then the edge filler, then 6 layers of glass on the inside. I plan on refrigerating the resin, pre-cutting and dry fit checking, and having the resin/hardener for each layer already set out in premeasured cups. Also have most of the bag in place and leak checked before I start.

Any suggestions for filler material from CSC?

I have been doing a lot of web surfing for info since I haven’t been able to get to do anything useful on the boat and found a couple of good articles that others may be interested in.
Here is an article from Bruce Pfund about core construction that is really good but tends to focus on foam cores: http://www.bpspecialprojects.com/PDF...20PROBLEMS.PDF
The same guy also wrote one about proper penetrations through cores: http://www.bpspecialprojects.com/PDF...0CLOSEOUTS.PDF

[bigeasy1]

Man o man, this is making me relive my 3 yr Tsunami restoration.Great to see that you are documenting the project with lots of photos.
They are just awesome boats, and although the work to restore is brutal,but the end result far outweighs the back breaking process.
The old saying "quality is remembered long after cost is forgotten" holds very true to these great hulls.

I think doing the transom from the inside as you are , is the best way as you dont compromise the integrity of the hull.I also did my transom from the inside, I made the cuts in the middle of the hawse pipe cutouts, pulled the rub rail back to amidships, and lifted the rear cap off.
Kinda wished I went with the coosa like you did instead of marine plywood.these boats are stern heavy so any weight savings in the rear, is a good thing, especiall with the weight of the I/O and engine.

Since you are doing the work with epoxy, you may be better off making your own putty for the radius at the inner transom face to hull joint.you could mix up some epoxy resin with some cabosil and some milled glass fibre.it would make a nice strong putty that you could easily apply with a nice radiused edge.
I did the glass layup with vinylester on the transom to the hull, and used hull and deck putty from Merton Fiberglass www.mertons.com although it wouldnt work in your case , as you are using epoxy and the hull and deck putty is a polyester based putty that wouldnt cure properly over an epoxy resin

Looking forward to your progress, keep the pics coming, and thanks for sharing and saving another awesome classic.

[FLexpat]

Since I’m doing vacuum bagging, I need a good resin trap in case I screw up on how much epoxy resin I use. Made this out of a pressure cooker. I know it is too big but this is the best cheap solution I could come up with. It holds a vacuum but I haven’t gotten any resin in it yet. I sprayed the inside with silicone spray to make chipping resin out easier.

Went ahead and cut out the scupper blocks – Starboard was dry and port was mush.

I leveled the edge gaps with thickened epoxy and covered it with peel ply to minimize blush.
Cut 1.5” Coosa to fit with the template I made from pegboard – made the tolerances much closer that the 1+” gap that the original plywood had on the edges. I did a fit check after leveling the edge gaps too. The problem with this approach thumped me later…

Scarfed the top edge of the Coosa to tie in the glass to the transom on the top edge – used a power planer. I drilled through where the stern light goes and put in a lift loop of ¼” nylon. That made moving it much easier with a lift.

Drilled 36 1” diameter holes in the Coosa and cut matching plugs out of 1” fiberglass rod. I was amazed at how well that worked – they all fit perfectly and were flush on both sides (within ~0.02”).
Cut out a section in the center for a section of solid glass to go around the drive – that was a PITA to get right.

Epoxied in all the rod and plate inserts and vacuum bagged it – that worked pretty well.

In a couple of spots the absorber got epoxied to the Coosa where it slipped – I now make sure peel ply or release film separate the absorber material from the part. I intended to keep peel ply on and drill through it in a couple of places – the peel ply knotted up on the drill – I’ll show plan B when I do it next time.
Did a ‘final’ fit check with the Coosa – looked great – (I am such a sucker sometimes).
It was a BAD idea to stretch 6 mil plastic across a sheet of Coosa to make a layup table – the small wrinkles in the plastic meant that I didn’t get the layup I wanted. I will spend the $35 for a 4x8 sheet of melamine board before the next work session.
I used these measuring cups with a sloped measuring surface for the resin and hardener – they worked GREAT.

I cleaned them with denatured alcohol – I think acetone would wreck them. I also got a package of 4 silicone spatulas for $5 – used 1 for resin, 1 for hardener, and 1 for mixed epoxy application on the inside of the transom – they really helped in mixing and in getting the layer on the inside of the transom even (I followed up with a notched trowel). The 10” length of the handle helped me on the transom too.
Coosa core layup on the table was 2 layers of 10 oz cloth, the Coosa Core, then 1708, 1808, 1708.
Here it is before resin on the 1st layer of 1708.

Bagged it – the heavy glass on top of the Coosa came out great – my target was 40% glass (by weight) and I was pretty close – I calculated how much I would need to hit target and mixed about 5-10 oz extra for each batch and didn’t use all of the extra epoxy. I had the mix quantities for each layer up on my laptop screen in the shop to minimize mix screw-ups – it worked this time.
My intention was to put the Coosa core in the transom green but I didn’t notice that some of the 1708/1808 stuck out a little from the edge… and it gets pretty strong even if it isn’t cured. Didn’t get pictures of this UGLY part – the near disaster: I put a nice layer of thickened epoxy on the inside of the transom and lifted the core into place – almost… It was too wide by ~3/16” because of the glass on the edge (upper left corner of last pic). No problem – 15+” of vacuum will pull it in – WRONG. There was a ½” gap between the core and the transom skin because the core was hung up on the edges.
Managed to get it out before cure.
Now I get to re-grind the inside of the transom, cleanup the 10 oz side of the Coosa, and do this again.

[FLexpat]

Put the Coosa core in the transom this weekend.
First put more 1708 and 1808 on the core (both sides) – vacuum bagged it – I REALLY like how that works on large flat surfaces – I got very close to 40% glass in all of the layers.

I calculated exactly how much resin each layer would need for a 40% glass ratio (based on cloth weight) then mixed a bit more. I used a fiberglass roller to work the excess out after I spread it. I was able to work carefully even though I was using a fast hardener for strength since I had resin and hardener premeasured and chilled for each layer. Chilling gives more working time but remember not to chill below the dew point or you have a problem.
I did each side as a separate vac bag layup. Here is a close-up of the finished layup.

Each side had peel ply, bleeder/breather and a plastic sheet on top with a layer of 6 mil polyethylene sheeting on bottom. I taped the top sheet of V-fold plastic to the poly that covered my work table. Polyethylene sheeting melts at about 225-250F – a puddle of resin gets hotter than that if not dealt with – don’t ask – I was very lucky it did not screw up the layup. Another thing about the poly – the static charge on it attracts every bit of dust and dirt. The V-fold stuff doesn’t do that.
When I had drilled into peel ply a while ago where I did not vac bag, the peel ply knotted up on the drill bit. I knew I was going to use bolts in several places later to pull it in tight while I bagged it, so I put a piece of plastic on the resin where the bolts would go before I put the peel ply cloth down. I cut the peel ply out of the way before drilling but left most of the peel ply in place when I put the core into the transom. I later figured out that the plastic patches was wasted effort – the peel ply cloth soaks up enough resin when it is vac bagged that it won’t knot up on a drill. Now I get to sand the smooth spots where the plastic was.

A note about peel ply fabric – it seems to stop/reduce blush even without vac bagging and it really helps get to a good glass/resin ratio with vac bagging – and there is no blush with vac bagging – I know because the fast hardener blushes a lot without it. Also it protects the surface from dirt during/after cure and the finish is great for applying glass to later on. You can wait weeks to pull it if you want to. The bleeder fabric does a good job of soaking up stray resin too – I did not end up with any in my resin trap even with 18-20” of vacuum on all the flat layups. The downside is a whole lot of waste material that has been soaked with resin and hardened.

I was glad I had the bolts as backup for vacuum to put the core in the transom – I have not mastered sealing the bag well on the transom with the constraints of fast resin, short time, and poor access – I had leaks and could only get about 8” of vacuum with 2 5cfm pumps. The bolts prevented a disaster. I should have done a practice bag too. Even with the lift for the core, 2 sets of hands was not enough – I should have had 3. And from now on I will use Martins idea of bubble wrap with the bleeder fabric – it would have helped also. I mixed the cabosil in and pre chilled my resin in a fridge so that helped – it was 88F – without chilling, it would have set before I had the coosa fully in place. If I ever do another transom, I will use the outer skin as one side of the bag with the core as the other and just use some very wide tape on the edges and a couple of bolt holes or the drain plug hole for the vac ports – and test it first.
I used peel ply on the cabosil fillets to prevent blush – more glass goes in in later.

Here it is after all the peel ply has been pulled. There are still a few gaps to fill but I ran out of silica for cabosil.

One note to all the guys who want to increase transom thickness on a 23 – there is not much room between the stern coolers (in the cap) and the transom – I did not see that problem coming. My new (lighter) core is ~.25” thicker than the old one as a result of the alternating layers of 1708 and 1808 so the cap won’t fit back on without some strategic grinding and you can’t just move the cap forward. Fortunately, the rear walls of the coolers are really thick and I have lots of recent practice with a grinder.

[Entourage]

Looking good flex

[martin]

Very nice... Yes I had major issues with vac bagging cause my tape would not stick well. I have learned to use 2" wide duct tape as a secondary sealant around the tacky tape it really helps seal abs keep things in place...
I have one air pocket I need to fix on the inside of transom... I will vac fill with epoxy
Great work.. And documentation.

[FLexpat]

Originally Posted by martin

I have one air pocket I need to fix on the inside of transom... I will vac fill with epoxy

I have a void about 1/16" thick, towards the top (around the stern light hole) that I will be doing a epoxy vac fill on too. It doesn't seem to be big enough to be a structural issue but it pisses me off and I'm going to fix it. Please be sure to post what you do - I have a lot to learn. Right now I am planning on using slow/thin epoxy and doing it a little like a modified RTM with the injection through the stern light hole.

Mike - thanks - yours looks great - where are your batteries? I didn't see them in the pics.

[Billpotter]

Looks good Flex; keep the pictures coming-