Thinking of building a new float and ride board, based on the Goya 118, that will hopefully be significantly lighter than my previous ones.
I was hoping to get a sheet of 20cm eps 70 as the core, but can't find any. I have been offered 10 cm sheets for about ?20 a sheet, so would need to glue them together in some way. My thoughts are to hot-wire 7 (or8) rocker/thickness templates and glue these together vertically, leaving 5 glue lines which wouldn't need any more hot-wiring, and minimal shaping.
The other way would be to glue the 2 sheets together to give the 20 cm thickness, but would then be faced with hot-wiring glue lines...... Yuk.
Following shaping, my schedule would be 4 oz top and bottom, 5mm pvc on the bottom, 3 on the deck, cut the rails off, and use pvc to rebuild (no vac bag) then s glass all over, with minimal carbon where needed.
This will take a while, it is currently -1 degree, in an unheated workshop! Any thoughts from the board builders much appreciated. Cheers, and windy new year to all.

I've tried this and it was not good . I've made boards without vac bagging and it will be heavier. Glueing sheets of eps together is horrible in more than one way . The glue lines are hard and make shaping a pain in the ass. You won't get the shape perfect and any imperfections will have to be bogged . You have to glue the pvc on with a thick layer of thickened resin which will add weight and use weights to hold it down. A thin layer of resin won't work. Any V or concave will be a hassle especially with 5 mm pvc. You have to make sure it is properly squashed down. There are ways but it's complex.The top is harder because it has a lot of curve . If you cut the rails off and replace with pvc it will weigh a ton. Then when you hand laminate you will use about double of laminating resin. Unless the blank is perfect and smooth. Adding about 20% weight . Having pvc rails will add more. And then add more because the blank will be lumpy needing lots of bog. After adding all the parts needed and consumables it will end up more expensive than a really good condition second hand board. And be heavy.
Sorry for the downer.
If you still want to make a board for fun , definitely use a one piece block of foam.
ps. You're going to make a lot of noise and mess. Foam and dust will go everywhere.

i'm with Imax, it's not ideal.

another option is higher density eps(24-28 kg/m3) . then hand laminate glass top and bottom. no pvc required.
with my builds i've used
2 layer 6oz volan + 1 layer 4oz glass on the deck
1 layer 6oz volan + 1 layer 4oz glass on the bottom.

0.6mm veneer to the foot strap area plus an extra layer 6oz at the nose. carbon stringers.
you can save a lot of weight by laminating the deck in one go and the bottom in one go. it's stronger too but takea more experience.
135lt float and ride I built was around 8kg. pretty much inline with off the shelf board.

it's an old school method but it works. there is a lot that will impact the strength of the board beyond the glassing schedule or foam density. board shape makes a difference

currently i'm building boards with a sandwich layup over lighter density foam, 13kg/m3 (no vac bag).
i use the sandwich on the deck only. pvc inserts for boxes etc. looking at ending up around 6.7kg for an 85lt board. which is about 300g heavier than off the shelf.
deck is 2 layers 4oz, pvc, 2 layer 4 oz.
bottom 3 layer 4 oz.
extra layers around nose and mast track with carbon stringers.

Think I'll have to learn vac-bagging!

Select to expand quote

jontyh said..
Think I'll have to learn vac-bagging!

I've only done board mods (tail, nose, etc) not a full board build but vac-bagging is, imho, so, so helpful. The ability to get constant and even pressure over a complex surface gives you much more flexibility in the shape and methods you use. No amount of tape, weights, etc can take its place. As well, things like peel-ply save you a lot of time in the finishing plus keep the build weight down. I know money is always an issue but, like most projects, the right tools really help.

This used to be a Starboard Freeformula '04 Bagging made doing the tail shapes and nose rocker so much easier. I'd done another conversion prior on another board and it was an absolute mess of tape and sanding.

Any time you can avoid glueing up a blank you should. That said I have done it recently to accomadate milling on CNC machine I have access to and at other times to use the only foam I could get. The best glue for the job is 3M 78 spray adheasive.
www.amazon.com/3M-78-Polystyrene-Insulation-Translucent/dp/B001EUOAGK/ref=sr_1_1_sspa?crid=JSPOUZOTBVIG&keywords=3m+78+spray+adhesive&qid=1704993853&sprefix=3m+78%2Caps%2C165&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
This is different from the more comon super 77 in that it will not eat the foam. If you follow the directions on the can it's bond is stronger than the foam. It sands and hotwires as if it is not there. I weighs virtually nothing once the solvents flash off. It's better to glue up than to not buid at all.

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Paducah said..

jontyh said..
Think I'll have to learn vac-bagging!

I've only done board mods (tail, nose, etc) not a full board build but vac-bagging is, imho, so, so helpful. The ability to get constant and even pressure over a complex surface gives you much more flexibility in the shape and methods you use. No amount of tape, weights, etc can take its place. As well, things like peel-ply save you a lot of time in the finishing plus keep the build weight down. I know money is always an issue but, like most projects, the right tools really help.

This used to be a Starboard Freeformula '04 Bagging made doing the tail shapes and nose rocker so much easier. I'd done another conversion prior on another board and it was an absolute mess of tape and sanding.

Paducah! That's effing sic bro!!! Wow, nice work! Hows the ride?

Select to expand quote

Gestalt said..
i'm with Imax, it's not ideal.

another option is higher density eps(24-28 kg/m3) . then hand laminate glass top and bottom. no pvc required.
with my builds i've used
2 layer 6oz volan + 1 layer 4oz glass on the deck
1 layer 6oz volan + 1 layer 4oz glass on the bottom.

0.6mm veneer to the foot strap area plus an extra layer 6oz at the nose. carbon stringers.
you can save a lot of weight by laminating the deck in one go and the bottom in one go. it's stronger too but takea more experience.
135lt float and ride I built was around 8kg. pretty much inline with off the shelf board.

it's an old school method but it works. there is a lot that will impact the strength of the board beyond the glassing schedule or foam density. board shape makes a difference

currently i'm building boards with a sandwich layup over lighter density foam, 13kg/m3 (no vac bag).
i use the sandwich on the deck only. pvc inserts for boxes etc. looking at ending up around 6.7kg for an 85lt board. which is about 300g heavier than off the shelf.
deck is 2 layers 4oz, pvc, 2 layer 4 oz.
bottom 3 layer 4 oz.
extra layers around nose and mast track with carbon stringers.

How are you glueing the pvc to the deck ?

Select to expand quote

Imax1 said..

Gestalt said..
i'm with Imax, it's not ideal.

another option is higher density eps(24-28 kg/m3) . then hand laminate glass top and bottom. no pvc required.
with my builds i've used
2 layer 6oz volan + 1 layer 4oz glass on the deck
1 layer 6oz volan + 1 layer 4oz glass on the bottom.

0.6mm veneer to the foot strap area plus an extra layer 6oz at the nose. carbon stringers.
you can save a lot of weight by laminating the deck in one go and the bottom in one go. it's stronger too but takea more experience.
135lt float and ride I built was around 8kg. pretty much inline with off the shelf board.

it's an old school method but it works. there is a lot that will impact the strength of the board beyond the glassing schedule or foam density. board shape makes a difference

currently i'm building boards with a sandwich layup over lighter density foam, 13kg/m3 (no vac bag).
i use the sandwich on the deck only. pvc inserts for boxes etc. looking at ending up around 6.7kg for an 85lt board. which is about 300g heavier than off the shelf.
deck is 2 layers 4oz, pvc, 2 layer 4 oz.
bottom 3 layer 4 oz.
extra layers around nose and mast track with carbon stringers.

How are you glueing the pvc to the deck ?

Epoxy with structural fillers and masking tape

Select to expand quote

Gestalt said..

Imax1 said..

Gestalt said..
i'm with Imax, it's not ideal.

another option is higher density eps(24-28 kg/m3) . then hand laminate glass top and bottom. no pvc required.
with my builds i've used
2 layer 6oz volan + 1 layer 4oz glass on the deck
1 layer 6oz volan + 1 layer 4oz glass on the bottom.

0.6mm veneer to the foot strap area plus an extra layer 6oz at the nose. carbon stringers.
you can save a lot of weight by laminating the deck in one go and the bottom in one go. it's stronger too but takea more experience.
135lt float and ride I built was around 8kg. pretty much inline with off the shelf board.

it's an old school method but it works. there is a lot that will impact the strength of the board beyond the glassing schedule or foam density. board shape makes a difference

currently i'm building boards with a sandwich layup over lighter density foam, 13kg/m3 (no vac bag).
i use the sandwich on the deck only. pvc inserts for boxes etc. looking at ending up around 6.7kg for an 85lt board. which is about 300g heavier than off the shelf.
deck is 2 layers 4oz, pvc, 2 layer 4 oz.
bottom 3 layer 4 oz.
extra layers around nose and mast track with carbon stringers.

How are you glueing the pvc to the deck ?

Epoxy with structural fillers and masking tape

3 rolls of masking tape ,Mummification. Do you get the pvc to completely wrap the rails ?

If gluing vertically and using CNC, any thoughts on a hollow build?
Probably best for a very thick board using heavier foam but interesting none the less.

Select to expand quote

Imax1 said..

Gestalt said..

Imax1 said..

Gestalt said..
i'm with Imax, it's not ideal.

another option is higher density eps(24-28 kg/m3) . then hand laminate glass top and bottom. no pvc required.
with my builds i've used
2 layer 6oz volan + 1 layer 4oz glass on the deck
1 layer 6oz volan + 1 layer 4oz glass on the bottom.

0.6mm veneer to the foot strap area plus an extra layer 6oz at the nose. carbon stringers.
you can save a lot of weight by laminating the deck in one go and the bottom in one go. it's stronger too but takea more experience.
135lt float and ride I built was around 8kg. pretty much inline with off the shelf board.

it's an old school method but it works. there is a lot that will impact the strength of the board beyond the glassing schedule or foam density. board shape makes a difference

currently i'm building boards with a sandwich layup over lighter density foam, 13kg/m3 (no vac bag).
i use the sandwich on the deck only. pvc inserts for boxes etc. looking at ending up around 6.7kg for an 85lt board. which is about 300g heavier than off the shelf.
deck is 2 layers 4oz, pvc, 2 layer 4 oz.
bottom 3 layer 4 oz.
extra layers around nose and mast track with carbon stringers.

How are you glueing the pvc to the deck ?

Epoxy with structural fillers and masking tape

3 rolls of masking tape ,Mummification. Do you get the pvc to completely wrap the rails ?

i rebate a 3mm inlay to the deck area with a router extending to the start of the rail. The sandwich layer finishes flush and is easier to tape down. also, the fold in the bottom layer of glass where the rebate starts adds stiffness like a stringer.

by the time I've laid up rail tape and wrapped the top and bottom glass layers i end up with about 7 layers of cloth around the rail which seems pretty strong.


remember back in the days where we all sailed boards made from pu that only weighed 6-7 kg and lasted longer than some of the stuff made today.

Select to expand quote

utcminusfour said..

Paducah said..

jontyh said..
Think I'll have to learn vac-bagging!

I've only done board mods (tail, nose, etc) not a full board build but vac-bagging is, imho, so, so helpful. The ability to get constant and even pressure over a complex surface gives you much more flexibility in the shape and methods you use. No amount of tape, weights, etc can take its place. As well, things like peel-ply save you a lot of time in the finishing plus keep the build weight down. I know money is always an issue but, like most projects, the right tools really help.

This used to be a Starboard Freeformula '04 Bagging made doing the tail shapes and nose rocker so much easier. I'd done another conversion prior on another board and it was an absolute mess of tape and sanding.

Paducah! That's effing sic bro!!! Wow, nice work! Hows the ride?

Thanks, much appreciated. It's a bit nose heavy and I did not have time this summer to move the back straps back. On the list for a spring project. It's my fault for placing the straps in the same place as my 195cm board. It was an interesting project and well worth it, though, just for the lessons. Gives me a much great appreciation for all those (like you) who shape an entire board from scratch.

Select to expand quote

Grantmac said..
If gluing vertically and using CNC, any thoughts on a hollow build?
Probably best for a very thick board using heavier foam but interesting none the less.

A friend built a paulownia strip sup using eps ribs. the eps had holes.

Seemed to work however the timber strips take all of the load as the eps is sacrificial.

Select to expand quote

Gestalt said..

Grantmac said..
If gluing vertically and using CNC, any thoughts on a hollow build?
Probably best for a very thick board using heavier foam but interesting none the less.

A friend built a paulownia strip sup using eps ribs. the eps had holes.

Seemed to work however the timber strips take all of the load as the eps is sacrificial.

A wood board build has been something I've considered. Probably in a wavy windSUP rather than a board which I'd ever jump.

Select to expand quote

Grantmac said..
If gluing vertically and using CNC, any thoughts on a hollow build?
Probably best for a very thick board using heavier foam but interesting none the less.

Look closely at the pic in my post above and you can see circles on the vertical side of the part on the right. I was planning on building with XPS that weighed 2#/ft^3, inspired by all hollowed out home brew downwind boards being built these days. To make it work weight wise I cut circles and ellipses out of each slice. I changed my mind on the foam along the way and ended up with 1# EPS. I cut the first sheet leaving the holes in the file and in pushing on it after it was cut I was not comfortable that it was strong enough. Super light foam works when it sees mostly compressive loads, when it is thin and has to span gaps it is in bending and it's pretty risky with wimpy foam. So I cut plugs to fill them back in and keep the project moving forward, I cut the other half without the holes. With tougher foam on a high volume board it would be a great idea. All these holes are staggered but overlap to create a connected air space that would have gotten a vent. With 1# foam the holes do not save much weight and adds machine time. The glued up blank in the picks above is 145 liters and only weighs 4.5 lbs, This was fun and educational but SLOW! If my next board is this simple of a shape and built frpm 1# EPS I will use the CNC to cut hot wire templates and get a solid block of foam.

Select to expand quote

Gestalt said..

Imax1 said..

Gestalt said..

Imax1 said..

Gestalt said..
i'm with Imax, it's not ideal.

another option is higher density eps(24-28 kg/m3) . then hand laminate glass top and bottom. no pvc required.
with my builds i've used
2 layer 6oz volan + 1 layer 4oz glass on the deck
1 layer 6oz volan + 1 layer 4oz glass on the bottom.

0.6mm veneer to the foot strap area plus an extra layer 6oz at the nose. carbon stringers.
you can save a lot of weight by laminating the deck in one go and the bottom in one go. it's stronger too but takea more experience.
135lt float and ride I built was around 8kg. pretty much inline with off the shelf board.

it's an old school method but it works. there is a lot that will impact the strength of the board beyond the glassing schedule or foam density. board shape makes a difference

currently i'm building boards with a sandwich layup over lighter density foam, 13kg/m3 (no vac bag).
i use the sandwich on the deck only. pvc inserts for boxes etc. looking at ending up around 6.7kg for an 85lt board. which is about 300g heavier than off the shelf.
deck is 2 layers 4oz, pvc, 2 layer 4 oz.
bottom 3 layer 4 oz.
extra layers around nose and mast track with carbon stringers.

How are you glueing the pvc to the deck ?

Epoxy with structural fillers and masking tape

3 rolls of masking tape ,Mummification. Do you get the pvc to completely wrap the rails ?

i rebate a 3mm inlay to the deck area with a router extending to the start of the rail. The sandwich layer finishes flush and is easier to tape down. also, the fold in the bottom layer of glass where the rebate starts adds stiffness like a stringer.

by the time I've laid up rail tape and wrapped the top and bottom glass layers i end up with about 7 layers of cloth around the rail which seems pretty strong.


remember back in the days where we all sailed boards made from pu that only weighed 6-7 kg and lasted longer than some of the stuff made today.

I have been thinking about doing this in the standing area. It looks like a easy way to get a light and tough deck.

VERY cool, especially for a board which won't get a full sandwich construction.

Select to expand quote

utcminusfour said..

Gestalt said..

Imax1 said..

Gestalt said..

Imax1 said..

Gestalt said..
i'm with Imax, it's not ideal.

another option is higher density eps(24-28 kg/m3) . then hand laminate glass top and bottom. no pvc required.
with my builds i've used
2 layer 6oz volan + 1 layer 4oz glass on the deck
1 layer 6oz volan + 1 layer 4oz glass on the bottom.

0.6mm veneer to the foot strap area plus an extra layer 6oz at the nose. carbon stringers.
you can save a lot of weight by laminating the deck in one go and the bottom in one go. it's stronger too but takea more experience.
135lt float and ride I built was around 8kg. pretty much inline with off the shelf board.

it's an old school method but it works. there is a lot that will impact the strength of the board beyond the glassing schedule or foam density. board shape makes a difference

currently i'm building boards with a sandwich layup over lighter density foam, 13kg/m3 (no vac bag).
i use the sandwich on the deck only. pvc inserts for boxes etc. looking at ending up around 6.7kg for an 85lt board. which is about 300g heavier than off the shelf.
deck is 2 layers 4oz, pvc, 2 layer 4 oz.
bottom 3 layer 4 oz.
extra layers around nose and mast track with carbon stringers.

How are you glueing the pvc to the deck ?

Epoxy with structural fillers and masking tape

3 rolls of masking tape ,Mummification. Do you get the pvc to completely wrap the rails ?

i rebate a 3mm inlay to the deck area with a router extending to the start of the rail. The sandwich layer finishes flush and is easier to tape down. also, the fold in the bottom layer of glass where the rebate starts adds stiffness like a stringer.

by the time I've laid up rail tape and wrapped the top and bottom glass layers i end up with about 7 layers of cloth around the rail which seems pretty strong.


remember back in the days where we all sailed boards made from pu that only weighed 6-7 kg and lasted longer than some of the stuff made today.

I have been thinking about doing this in the standing area. It looks like an easy way to get a light and tough deck.

Was the only way I could get my head around using sandwich construction without vac bags. A lesson learnt is to allow 5mm tolerance around the inlay.

Any ideas if this would be ok as a vac pump? it seems really cheap at ?88

Prob not as i gather for a first cheap setup you will use a bleeder valve to achieve the right vacuum (rather than a controller to turn on and off)
That means continuous running, and little oil-less pumps don't like it much

Ebay 1/4hp 5cfm oiled pump about $150

just won a Becker vt 4.8 for continuous running, 80 sterling..... hope it will do, if not, ill sell it on!

Patrik brand make the air inside boards using honeycomb walls. Hollow. Very labour intensive but strong and light.

For the foam glue, would it make sense to glue in a divinicell or similar stringer to reinforce the foam especially through the middle?

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berowne said..
For the foam glue, would it make sense to glue in a divinicell or similar stringer to reinforce the foam especially through the middle?

I did that on a vac-less one i made, worked well, but still heavier than i was aiming for!

What weight are you chasing?

Select to expand quote

berowne said..
For the foam glue, would it make sense to glue in a divinicell or similar stringer to reinforce the foam especially through the middle?

No, as it adds no strength in a sandwich board and glue lines make shaping really hard. PVC stringer makes it even worse and cant hotwire

not after a specific weight, just in the region of professionally made customs (approx 8 kg for a 115L?) I cut the pvc stringer exactly to size before gluing it in the blank, so it acted as a guide. It was more to widen the blank slightly rather than strength, as i didn't have enough foam left to get to the width i wanted (by about 20mm)I won't use it in a sandwich construction.
I now have a vac pump, so will get to know the process with that before attempting to use it for a new board. I have also found a polystyrene glue in the UK which seems to work really well, and can be hot-wired easily. The 3m version is not available here, so happy to find something.

I reckon give it a go. Everyone I've ever spoken to builds boards differently.