Bowchow

composite floor boards?

Recommended Posts

Looking for a solution to re make an existing floorboard set up on a 38' racer cruiser (mostly racer). Floorboards are typical teak/holly at the moment and have seen better days. About 1/2" thick, so we have some room to play with.

 

Was debating starboard, but another boat I work on has this and there is a decent amount of flex. Just seeing if anyone else has done anything similar that isn't crazy expensive (time and cost wise)

 

 

IMG_4672.jp2

Share this post


Link to post
Share on other sites

Starboard would be about my last choice.  Relatively heavy and expensive, lots of flex, hard to keep clean I would suspect.

Back in the days of the Boeing Surplus store, I believe some people were able to buy thin carbon/nomex panels for exactly this purpose (and other cool stuff) for quite cheap.  Which I suppose isn't really relevant these days because Boeing closed the store down several years ago.  They still have an on-line store, but seldom does anything worthwhile come up IMO, or maybe it just gets snapped upped immediately.

  • Like 1

Share this post


Link to post
Share on other sites

PLywood is easy to make, but has limited life, as you’ve learned.

I’d consider planks of a decay resistant solid wood like Teak and other tropical hardwoods will serve well.  THey’re heavy.  The cedars are decay resistant, lighter and less speedy.  Alaskan yellow cedar, unfinished, would be my choice. 

Share this post


Link to post
Share on other sites

Plywood will last if you know how to treat it properly.

I have a friend with a boat that has been on a mooring for a bit over 16years with ply floor boards they still  look like new. 

  • Like 1

Share this post


Link to post
Share on other sites

Do you want the wood look or do you want to to do away with wood all together? 

It all comes down to cost per square foot. Fiberglass covered foam core (1/2") will cost about $15 per square foot in materials and probably the same in labor all considered. if you did it yourself it would be less. 

Share this post


Link to post
Share on other sites

Boat is 27 years old, still has her Divinycell/Lonseal laminate boards. They a bit beat up but still going strong (and light). Not sure what they used to laminate them together. 

Share this post


Link to post
Share on other sites

Marine ply coated in epoxy and painted will be the most cost effective long term solution.  It's super stable and easy to work.

Share this post


Link to post
Share on other sites

 

bluewater2.jpg

Coosa BlueWater 26 lbs per cu ft

Just paint this stuff and add some non-skid. 30% lighter than plywood. Cut and route with woodworking tools.

Coosa Nautical board. 20 lbs per cu ft. Developed to be a replacement for ply in motorboat transoms. Different densities and percentages of woven roving incorporated in the core.

nautical1.jpg

 

They are building whole boats with it now. I designed a kit boat for a little lightweight 13' flats skiff using this stuff. A bit more expensive that good Okume marine ply.

Marine026.jpg

 

 

 

 

Another brand is PenskeBoard.

Share this post


Link to post
Share on other sites
7 hours ago, Rasputin22 said:

 

 

Coosa BlueWater 26 lbs per cu ft

Just paint this stuff and add some non-skid. 30% lighter than plywood. Cut and route with woodworking tools.

Coosa Nautical board. 20 lbs per cu ft. Developed to be a replacement for ply in motorboat transoms. Different densities and percentages of woven roving incorporated in the core.

 

 

Ohhhh I like this. Think I found my material!!  Thank you all!

 

Share this post


Link to post
Share on other sites
Just now, Bowchow said:

 

 

Ohhhh I like this. Think I found my material!!  Thank you all!!!!

 

I spent a lot of time and effort researching the material and talked with the guys at the factory which makes in here in Alabama. I also checked out the power boat guys over on the Hull Truth who have a huge body of experience. Lots of transom replacements 'rotted ply' and then once the DIY guys worked with it a bit they are doing consoles, fish boxes, Console Hard Tops and lots of improvements on the boats. I even spoke with commercial fishermen that are replacing worn out decks and the are merely adding extra FG on the top side which gets all the wear and tear from traps and fishing gear. 

    Let me know what you figure out and I can perhaps help with specing out the laminates if any that you need. I have a calculator that will work with the Coosa and let you see how much weight and stiffness you get for a given panel size according to what laminates you add. 

  • Like 2

Share this post


Link to post
Share on other sites

That depends on which Divinycell, they make it in various densities (like most foam core options). The Coosa board looks like a really nice plywood replacement for use in wet environments!

 

 

Share this post


Link to post
Share on other sites
18 hours ago, Rasputin22 said:

I spent a lot of time and effort researching the material and talked with the guys at the factory which makes in here in Alabama. I also checked out the power boat guys over on the Hull Truth who have a huge body of experience. Lots of transom replacements 'rotted ply' and then once the DIY guys worked with it a bit they are doing consoles, fish boxes, Console Hard Tops and lots of improvements on the boats. I even spoke with commercial fishermen that are replacing worn out decks and the are merely adding extra FG on the top side which gets all the wear and tear from traps and fishing gear. 

    Let me know what you figure out and I can perhaps help with specing out the laminates if any that you need. I have a calculator that will work with the Coosa and let you see how much weight and stiffness you get for a given panel size according to what laminates you add. 

I was scrolling to the bottom to add the same input. We have started using it ALMOST exclusively for repairs where we once used plywood- decks, transoms, bulkheads, etc. The stuff is pretty amazing and really easy to work with.

We used to use the Nida as listed above also (and still do in certain applications) but the Coosa ease of workability, price, etc means it is our go-to now.

Share this post


Link to post
Share on other sites

Tested some panels. It's got longevity bond issues.

 Nothing sticks to the core. Something about plastic welding core to skin is a turnoff

 

 Restored some Bertram 25's. The Coosa is very popular with those guys as you noted. 

Share this post


Link to post
Share on other sites

Yes Peter, I have experienced the same with the NidaCore poly cell material. The used to claim that the fg scrim/veil that they hot sinter via a collander into the surface of the blown poly creates a bond layer for any subsequent skin laminations. But that really doesn't seem to get the sort of 'tooth' that is needed especially on panels that are subject to slamming loads. I had the whole underside of the bridgedeck of a 55' powercat get blown into shreds due to the NidaCore on a tough delivery to the VI when crossing the Mona Passage. The topsides weren't much better for the propensity of the hollow in the honeycomb to let water in from just about any joint of fastening. I drilled for a EBIRB bracket and water started squirting out in may face after going through the outer skin. It pissed for nearly an hours and then dribbled for a couple of days! 

  • Like 1

Share this post


Link to post
Share on other sites

Quick update, the owner gave the go ahead for the project.

 

I'll be ordering materials next week and keep you guys updated on the progress.

Share this post


Link to post
Share on other sites

What did you end up going with? I need to replace the boards that go over the engine on my cat30.  I also need to build a new table.  This seems ideal for both.  The span is about 3 feet on the engine boards and 4 feet on the table and I'm worried about flex.

Share this post


Link to post
Share on other sites

FWIW, I did the math on replacing my floor boards with .75" NidaCore panels structural fiberglass/honeycomb laminates.  https://www.merrittsupply.com/product/nida-core-structural-honeycomb-fiberglass-laminated-panels-h8pp/

It came out to approx 75 lbs of weight savings for around $350 + shipping, which is less than 1/2 of a percent weight savings. Considering it's all below-waterline weight, I doubt it's worth it.

Share this post


Link to post
Share on other sites

Another option I considered was routing out a grid pattern on the underside of the floor-boards, taking away about 1/2 - 1/3rd the depth. I think with a little engineering, you could cut about 50% of the weight, or around 50lbs for just the cost of time and a router bit. But again, chasing diminishing returns - there's probably lower-effort gains to be made by trimming down the toolbox or finding thinner friends.

Share this post


Link to post
Share on other sites
On 10/2/2019 at 10:44 AM, Rasputin22 said:

 

bluewater2.jpg

Coosa BlueWater 26 lbs per cu ft

Just paint this stuff and add some non-skid. 30% lighter than plywood. Cut and route with woodworking tools.

 

What am I missing? 1 4'x8' 3/8" panel is one cubic foot. From Boulter Plywood, their 7-ply okoume weights 28lbs. Per Atlantic Plywood, their 5-ply is also 28lbs. CLC Boats (5 ply), is 31lbs. Not seeing the weight savings.

Share this post


Link to post
Share on other sites

Occume plywood is very light - fir or other typical exterior ply is much heavier, and other types of marine ply (meranti, sapele) are somewhere in between. So 30% lighter than a heavy plywood is not unreasonable.

Share this post


Link to post
Share on other sites

One has to look at the strength to weight ratio, and the stiffness to strength ratio, not just the raw weight or raw density of the material. Without digging, I’m speculating the Coosa board has 30% or maybe greater strength than standard marine plywood. It’s also inherently waterproof, which most wood products are not.

Also, they make a lighter 15 lb/ft3 version: https://www.merrittsupply.com/product-category/plywood-composite-panels/coosa-panels/

Share this post


Link to post
Share on other sites

Coosa is great, but last time I checked it was spendy.   Just checked one place on-line and got $342 USD for a 4 x 8 sheet of 1/2".   

Mind you, even fake teak and holly ain't cheap either.

Share this post


Link to post
Share on other sites
4 hours ago, Rain Man said:

Mind you, even fake teak and holly ain't cheap either.

Last time I checked, in the UK, the Teak & Holly vinyl flooring that you stuck to floorboards was actually more expensive then real teak & holly. Significantly so.

Share this post


Link to post
Share on other sites

Glass the plywood and it will be heavier than the equivalent Coosa. Don't glass the ply and it will rot in time. Coosa is a favorite for replacing rotten outboard boat transoms. 

Share this post


Link to post
Share on other sites

Fiberglass Supply in Burlington, WA no longer sells Nidacore, but now sells a similar product called Plascore - $72 for a  1/2" - 4'x8' sheet or $83 for a 3/4" sheet.  http://www.fiberglasssupply.com/Product_Catalog/Core_Materials/core_materials.html  Cheap as chips - disregarding freight, but they would probably cut it for a minimal charge.  I have nothing but good things to say about this supplier.

Would have to apply 6 oz cloth to each skin, but you have an inexpensive featherweight panel.

Could also use poly instead of epoxy and use 3/4 oz CSM.  Total material cost well under $100.

First time I've been to the Plascore web-site in a long time, but I just noticed they also manufacture a line of honeycomb panels where the skin is glued to the honeycomb rather than the typical lamination.  Their web-site https://www.plascore.com/honeycomb/honeycomb-panels/ indicates they have a variety of skin/honeycomb material combos:

Skin Materials: • Aluminum • Stainless Steel • High Pressure Laminate • Glass/Epoxy Prepreg • G10 Fiberglass • For other materials, please contact us.

Honeycomb Cores: • Aluminum (Commercial and Aero/Military Grade) • Stainless Steel • Nomex® (Commercial and Aero/Military Grade) • Kevlar® (Aero/Military Grade) • Polypropylene • Polycarbonate

Not sure who sells the panels or the prices, but I would think Fiberglass Supply is a possible source even though not advertised on their web-site.

 

Share this post


Link to post
Share on other sites
On 10/2/2019 at 10:31 AM, Rasputin22 said:

Coosaboard with appropriate skins.

Coosa is pricy 

Share this post


Link to post
Share on other sites

Why not divinycell (H80) with skins in poly? 2 layers of 600gm biaxial per side would likely be plenty. Lighter and likely cheaper price than Coosa

Share this post


Link to post
Share on other sites
7 hours ago, Will1073 said:

Why not divinycell (H80) with skins in poly? 2 layers of 600gm biaxial per side would likely be plenty. Lighter and likely cheaper price than Coosa

Because you have to make them yourself.  This is the dilemma that everyone trying to solve this problem runs into.  Pay $$$ for Coosa or put in the hours to make them.  A fellow racer around my hood made his own and they turned out great, but he said it was a lot of work to get them right.  What is your time worth?

If I was spending someone else's money on the job I would definitely go Coosa.  

Share this post


Link to post
Share on other sites
16 hours ago, Will1073 said:

Why not divinycell (H80) with skins in poly? 2 layers of 600gm biaxial per side would likely be plenty. Lighter and likely cheaper price than Coosa

With a 14" max unsupported span, what thickness divinycell would you go with?

Share this post


Link to post
Share on other sites
9 hours ago, Rain Man said:

Because you have to make them yourself.  This is the dilemma that everyone trying to solve this problem runs into.  Pay $$$ for Coosa or put in the hours to make them.  A fellow racer around my hood made his own and they turned out great, but he said it was a lot of work to get them right.  What is your time worth?

Sailboats are a hobby or pastime - why do so many people price their time working on them as if it was employment?

Similar mindset to thinking about the money spent on them as an investment I guess.

  • Like 2

Share this post


Link to post
Share on other sites
12 minutes ago, SloopJonB said:

Sailboats are a hobby or pastime - why do so many people price their time working on them as if it was employment?

Similar mindset to thinking about the money spent on them as an investment I guess.

I think it is a question of what stage of life you are at.  For the longest time I was in the "have money but no time" stage.  Now I am in the "have time but no money" stage.  The choice would be easy for me now.

Share this post


Link to post
Share on other sites
8 hours ago, KnockedDown said:

With a 14" max unsupported span, what thickness divinycell would you go with?

14” in both directions? 1/2” is likely fine

Share this post


Link to post
Share on other sites

The short span governs the design. If the board is 14" long x 72" wide and supported on the long edges, it's effectively a 14" wide panel. The length doesn't matter really

  • Like 2

Share this post


Link to post
Share on other sites
On 10/24/2020 at 3:59 PM, Will1073 said:

Why not divinycell (H80) with skins in poly? 2 layers of 600gm biaxial per side would likely be plenty. Lighter and likely cheaper price than Coosa

For a cabin sole, 2 layer of 600gm (2 lams of 18 oz) is more than sufficient. 1 layer is more than sufficient.

10 hours ago, KnockedDown said:

With a 14" max unsupported span, what thickness divinycell would you go with?

1/2" divinycell is more than plenty.

I home tested some 28" long hatch covers I made of 1/2" 2 lb EPS foam with single lams of 6 oz cloth.  2 ft unsupported span and stood on one foot in the middle with my 220 lb and the compression side buckled.  Straightened it out and added a second lam of 6 oz on the compression side and it was fine.  It bowed a fair bit but didn't buckle, but the span was almost twice as long as the 14" in this case.

Not that I would recommend such a layup - but 1/2" Divinycell  with a single lam of 600 gm on each side should be sufficient.

Share this post


Link to post
Share on other sites
4 hours ago, 12 metre said:

For a cabin sole, 2 layer of 600gm (2 lams of 18 oz) is more than sufficient. 1 layer is more than sufficient.

1/2" divinycell is more than plenty.

I home tested some 28" long hatch covers I made of 1/2" 2 lb EPS foam with single lams of 6 oz cloth.  2 ft unsupported span and stood on one foot in the middle with my 220 lb and the compression side buckled.  Straightened it out and added a second lam of 6 oz on the compression side and it was fine.  It bowed a fair bit but didn't buckle, but the span was almost twice as long as the 14" in this case.

Not that I would recommend such a layup - but 1/2" Divinycell  with a single lam of 600 gm on each side should be sufficient.

I'm curious - epoxy or poly?

Share this post


Link to post
Share on other sites
24 minutes ago, Rain Man said:

I'm curious - epoxy or poly?

For the EPS core?  Epoxy.  Poly will dissolve EPS instantly upon contact.

But dang those were featherlight covers.

Share this post


Link to post
Share on other sites
9 hours ago, 12 metre said:

For the XPS EPS core?  Epoxy.  Poly will dissolve EPS instantly upon contact.

But dang those were featherlight covers.

Sorry, I meant XPS.

Share this post


Link to post
Share on other sites
15 hours ago, 12 metre said:

For a cabin sole, 2 layer of 600gm (2 lams of 18 oz) is more than sufficient. 1 layer is more than sufficient.

1/2" divinycell is more than plenty.

I home tested some 28" long hatch covers I made of 1/2" 2 lb EPS foam with single lams of 6 oz cloth.  2 ft unsupported span and stood on one foot in the middle with my 220 lb and the compression side buckled.  Straightened it out and added a second lam of 6 oz on the compression side and it was fine.  It bowed a fair bit but didn't buckle, but the span was almost twice as long as the 14" in this case.

Not that I would recommend such a layup - but 1/2" Divinycell  with a single lam of 600 gm on each side should be sufficient.

You’re correct, but I wouldn’t want to drop anything on that. 

Share this post


Link to post
Share on other sites
On 10/2/2019 at 7:44 AM, Rasputin22 said:

 

bluewater2.jpg

Coosa BlueWater 26 lbs per cu ft

Just paint this stuff and add some non-skid. 30% lighter than plywood. Cut and route with woodworking tools.

Coosa Nautical board. 20 lbs per cu ft. Developed to be a replacement for ply in motorboat transoms. Different densities and percentages of woven roving incorporated in the core.

nautical1.jpg

 

They are building whole boats with it now. I designed a kit boat for a little lightweight 13' flats skiff using this stuff. A bit more expensive that good Okume marine ply.

Marine026.jpg

 

 

 

 

Another brand is PenskeBoard.

Awesome stuff, and it's not made in China. 

Share this post


Link to post
Share on other sites

I've made these... They use a 3d printed core with a carbon cloth epoxy laminated on... We did 5 panles and managed to remove just short of 7kgs..

Hope this helps

Regards

TIm

IMG-20200504-WA0000.jpg

IMG-20200524-WA0004.jpg

Share this post


Link to post
Share on other sites

What is a "3D printed core"? Some sort of honeycomb? What is it made from?

Share this post


Link to post
Share on other sites

I'll admit in a moment of OCD (OK, a lifetime of OCD for me) we did composite floorboards in my boat. Vacuum bagged carbon over balsa with teak surrounding the edges of the balsa. Then an overlay of 1/4" of teak and holly. They are lighter than solid wood, but not all that light. They do span up to 3' in places. The balsa is the only structural wood on the boat. Chose balsa because it is very stiff, and very good in compression. Here they are laying out the teak and holly to make sure it is all grain matched across the breaks. 

IaYn7T5.jpg

  • Like 1

Share this post


Link to post
Share on other sites

How would you finish Coosa board? Just sand and paint it? Seal the edges first? Coat the whole thing?

Share this post


Link to post
Share on other sites
19 hours ago, Zonker said:

What is a "3D printed core"? Some sort of honeycomb? What is it made from?

It's a plastic printed honeycomb...

Regards

Tim

Share this post


Link to post
Share on other sites

I'd coat with a thin layer of glass then paint. It's pretty dense but it is a foam. The glass layers don't seem to be on the surface.

But it is expensive. If you're trying to save weight use regular PVC type foams + glass.

coosa-composite-board-bluewater-26.jpg?q

Share this post


Link to post
Share on other sites

1/2" poly honeycomb with DB 170 each side weighs about 0.95 lbs/ft2 with a duratec primer surface. Use a sheet of 3/4" melamine as a mold and vacuum bag it. You can gelcoat the mold instead of the duratec but it will be a bit heavier.

  • Like 1

Share this post


Link to post
Share on other sites
On 10/3/2019 at 7:07 AM, voodoochile said:

This is what we used.  Very light, easy to shape.  We glued a non skid to it but you could paint it.  https://www.merrittsupply.com/product/nida-core-structural-honeycomb-fiberglass-laminated-panels-h8pp/  .  38' sailboat, going on 10 years.  

NidaCore-Laminated-Panels.jpg

How are folks finishing the edges on panels like this?

Share this post


Link to post
Share on other sites

What we did on my carbon/balsa floorboards was to let in teak all around the edge. We did it mostly while laminating the panel, however a couple had to be cut down and in that case the core was rebated and the teak glued in. Same can be done with any cored material. My reasoning was I wanted a durable edge that was unlikely to rot (or chip or crumble as filler might) and strong enough to put fasteners through without crushing (on an offshore boat you want the floorboards fastened).

Share this post


Link to post
Share on other sites

image.png.c85035370a4704d9dfe2cf302adc3d91.png

image.png.6bee18f358c7bcf6d1a9ea98e9cc93e7.png

image.png.67964ea56498b1aee5fe61760f7dc098.png

Share this post


Link to post
Share on other sites
On 1/3/2021 at 9:22 PM, Steve said:

1/2" poly honeycomb with DB 170 each side weighs about 0.95 lbs/ft2 with a duratec primer surface. Use a sheet of 3/4" melamine as a mold and vacuum bag it. You can gelcoat the mold instead of the duratec but it will be a bit heavier. 

Our floorboards weigh approx 2lbs / ft, at 3/4" thick, for a total weight of 120lbs.  So this is roughly 33% lighter weight / volume.  It would be a lot of work to save 60lbs, but maybe worth it once other weight savings options are exhausted.

(Of course, you're going to have the boat re-measured after this right? B/c that's going to remove any rating benefit you get.)

  • Like 1

Share this post


Link to post
Share on other sites

There’s the perennial trade-off of weight vs. cost (or time).
Of course, a pound at the masthead has higher value than a pound in the keel, and floorboards are toward the low end of that range.
I’ve sometimes has SWAG estimates of how much a pound is worth to me.  On a light, but not racing multihull, I had $50/lb. in the back of my head, and on a 4KSB, it’d be a lot less.  
What’s a rational value?

 

Share this post


Link to post
Share on other sites
1 hour ago, Diamond Jim said:

What’s a rational value?
 

Wrong word to use around sailboats.

Share this post


Link to post
Share on other sites
2 hours ago, Diamond Jim said:

There’s the perennial trade-off of weight vs. cost (or time).
Of course, a pound at the masthead has higher value than a pound in the keel, and floorboards are toward the low end of that range.
I’ve sometimes has SWAG estimates of how much a pound is worth to me.  On a light, but not racing multihull, I had $50/lb. in the back of my head, and on a 4KSB, it’d be a lot less.  
What’s a rational value?

 

I race in a class with a minimum weight. I'm right there, so I keep on trying to imagine (legal) ways to make my cabin sole as heavy as possible, so I can remove weight elsewhere.

Share this post


Link to post
Share on other sites
On 1/8/2021 at 11:43 AM, occams_razor said:

How are folks finishing the edges on panels like this?

We used a thickened epoxy.  Troweled it in with a 4" mud knife, palm sanded it smooth.  Check with the panel mfg., they should have an appropriate product.  

Share this post


Link to post
Share on other sites
On 1/8/2021 at 11:37 PM, fucket said:

I race in a class with a minimum weight. I'm right there, so I keep on trying to imagine (legal) ways to make my cabin sole as heavy as possible, so I can remove weight elsewhere.

rout out small channels in the underside and fill them with ball bearings encased in epoxy?

Share this post


Link to post
Share on other sites

Ironwood floorboards?

Lead inserts? Or is that against the spirit of your particular rule?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now