I am building a SUP. CNC cut blank. 15kgs stringerless. I am going to start buy glassing the whole board in 80g glass. This will keep the rocker and allow me to create a composite bottom.
So the bottom is going to be 80g glass then 55kg 2mm thick high density foam. 2oz innegra then 160g woven flax.
The deck will be 80g glass then 4mm Paulownia wood. 125g glass and cork standing area.

As I said in the other thread I think you will still need a rocker spine for bagging it. One layer of glass might not stop all the potential bending.

I'm interested in the deck as the wood is very thick, most people would go a lot more glass and much thinner wood....... but not to say your way is wrong. What does the wood for the deck weigh?

Wet-out table and then roll the glass on will save you a lot as the first lam will suck a lot of resin

I'm keen to see it as your previous work looks amazing

Progress so far. Deck and bottom glasses. I put a layer of thickened epoxy on the foam before glassing. Recommended by the company I bought the blank off. First batch on the front half of the deck was a little too thick.
5mm too much rocker at the nose and about 7mm too much on the tail. I will block it when in the bag.
Next to figure out if I can get HD foam on the bottom and wrap it around the rail.

I probabably should have started with this.
This is a custom board for a large guy. 90ish Kgs, he also likes to take his girlfriend. She sits on the front. That is why its so big and flat on the deck.

couple of weights on the foam and a helper to keep it still. Then heat gun and bend....... It will

Great progress but yes need to rocker jig for vacuuming bottom.
The place that machined your blank should be able to cut.

I wouldn't bother with the thickened epoxy on the blank, its more a case of the pin holes after final laminating.
A bit unconventional with wrapping the rails from the bottom will involve more time but not to say it cant be done and will be easier on softer rail boards.
The ply does seem thicker, used to use 2mm gaboon on windsurf slalom boards and 0.8mm model veneer to do full deck and rail wrap with glass on top. Ply gets more form strength when curved. I guess the dude will be having his girl on the front so deck will be strong.

Question, did you build the hollow wood board in your profile?
That looks awesome

I have started shaping the high density foam to the rail. It's slow but getting there. I can't get any tape to stick to the HD foam.
I have bagged boards before and put a block under the nose and tail at the right height and lightly clamped it to keep the rocker. A weight in the middle. It might not give exactly the right curve along the board but it works.
4mm is what I put on. Then sanded so probably probably loose 1mm.
515 not sure which board. It might be hollow or wood bagged onto a blank.

With the tape you may have to go right across the foam then the ends will stick to the deck, but you use a lot more tape. The blocks give you close enough but for your own boards the rocker jig keeps accuracy if you are refining a shape. The screen shot of the hollow board

I think for what I am doing the blocks are close enough. I have bought some different types of tape. Don't mind if I use more.
Yes I designed and built that board years ago. Did a refit on it last year and it's still going strong. Very round bottom so not very stable but pretty fast in the flat. 13.5kgs. I still love it. The hollow wood board sensation is different.

I haven't had a flat water board but have to say awesome skills on the hollow wooden board.
With the tape I thought as an alternative to use webbing tiedowns with a cam lock so it pulls through one end and then you can reuse them.

Cant believe I didn't think of that. I have loads of them and use them to hold wood panels down whilst gluing them. Thanks.

Great solution when you already have them.
Can you post up some photos as I'm interested to see.
Will the ply be overlapping the foam on the rails?

I found some tape that sticks OK. The foam is in sheets so there will be 6 sheets. There are a 2 splits where the tape let go. I guess once its vac bagged and glued down it wont matter too much. I will give the tie downs a go next.
If I can get this stage finished in the evenings this week I can bag it on the weekend. Going to be difficult to get epoxy everywhere,everything held in place breather etc and in the bag. I have slow hardener.May have to bribe a friend with some beers.
I don't think the wood will overlap. I will use a tape on the rail at the end this will also cover the join.

You can always do a "dry run" vacuum bag and add allowable time for mixing

Little unconventional as would vacuumed the ply over the PVC sandwich but overlapping tape over join shoulder be good.
Could do wet out cloth on table and roll it up then out again that will get adhesion and you have to trim the excess cloth around the rails.

Don't be afraid to drill/puncture 3mm dia holes in the PVC foam prior to gluing the foam down. This allows air to escape from between the foam and EPS blank and allows excess glue to escape also. Usually done at 50mm centres, but best at 25mm centres like in the photo...

Thanks. That might take awhile !
I did notice some companies sell pre perforated foam. I couldn't find it in the lower density or thinner sheets though.
What's in the bag? Hollow SUP ?
Is it peel ply then breather.

So I am not having much success with the airex, it actually is airex I checked. In the middle of the board it's fine. The nose and tail just isn't happening.
I am only looking for impact resistance on the bottom. With the 4mm wood deck and at least 4 layers on the rails the board will be stiff enough.
The bottom was planned to be 80g glass,2mm 60kg airex, 2oz innegra and 160g flax.
How much impact resistance will I lose if I don't put the airex? Or are you better of with something that will give a bit. Like the Sunova vid where Bert pushes his thumb into the bottom of the board.

Just bend it with a heat gun first, then very minimal tape is needed, really it is just taped to help sliding it into the bag.

The way you have taped it, as the bag forces the airex to conform over your blank, the part of the airex that wraps around over onto the deck will slide over your tape and then you have tape laminated in under the airex = weakness.

Best to bend it first, then once you wet-out glass you put the pre-bent airex on, and with a helper one of you holds it down hard and the other person tapes right around the board (so tape is sticking to tape and it won't let go then).

As to holes - 3mm is crazy big and may lead to lots of filling. I just use dressmakers pins, and stab say 100 random holes through the hi density foam just before bagging. It takes 20 seconds.

BUT if you are only looking for impact resistance on the bottom, why foam all around? This is what we were getting at in your last thread - it is more conventional to vac bag the hi density foam on the bottom, then bag on the deck (wrapping around the rails). Thats why I posted link to my thread showing how. Its very unconventional so you may be best with just bagging on the bottom and not around rails.

One option it just have sandwich on the bottom. It's so fast to do

Weights or screw sheet down
Use heat gun, it will bend

Hi Darryl,
You are doing a deck and rails and your board is looking great.
But tarquin is going bottom and rails have an edge

Thanks for the info and photos. I will try again this morning.
Daryl I am doing what you describe but it just doesn't want to go around the sharp edge. I am using more heat but it doesn't seem to help.

Piece of piss. Don't know what you guys where going on about!
I wasnt heating it enough and holding it in place until it cooled.
Thanks.

This puts lots of holes in the foam pretty quick. It's for putting holes in wallpaper to remove it.

In the bag.
Now we wait.

Looking awesome, good job on that heat bending

Pretty happy in general. Some creases and gaps where the panels moved. Bit of sanding and filling.
The tape worked well on the deck to get a clean line.

Awesome
Hard part done

Looks tops :)

A good hard push all along the rails to make sure no "bubbles" where it didn't quite bond to the core (can see it a little near tail on port rail)

I've decided to be a little less fussy about getting my corecell exact as there will always be a bit of fill somewhere. Especially on complex tail shapes (and its going to get dinged there anyway) so a lump of filler on swallowtail point for example doesn't bother me much.

You're going to have a very strong board compared to the mass produced rubbish!

Some goodies arrived. UD flax/carbon tape. This is what I will use to cover the rail and join between the wood deck and rail.

Looks cool
So finbox, glass bottom and top, vent.
You painting or clear epoxy?