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Coosa Composite Board - Bluewater 26

As low as $110.31
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Key Features:

  • Great Decking and Transom Alternative - Do It Once - Do It Right!
  • Strongest and Stiffest Composite Panel with the Absolute Highest Strength-to-Weight Ratio
  • Consists of Polyurethane foam filled throughout with layers of continuous strand glass and woven fiberglass
  • Over 30% lighter than Plywood with equal superior structural integrity!
  • Absolutely No Water Rot! Mold, Mildew and Algae Resistant
  • 30% to 45% lighter than plywood
  • NO water rot or insect infestation
  • Less than 1% water absorption
  • Mold, mildew & algae resistant
  • NO Special Maintenance Required
  • Sanded for easy lamination
  • Easily fabricated with standard tools
  • Superior resiliency and endurance
  • Transoms
  • Decking
  • Swim Platforms
  • Sun Decks
  • Seating
  • Bench Cores
  • Bulkheads
  • Engine Covers & More!

Coosa Board Frequently Asked Questions

When replacing plywood decking, what thickness should I use?

The Short Answer

Bluewater 26 Coosa Board can be used as an exact replacement for any plywood decking as long as you use the same thickness installed in the same way (i.e. if your plywood was glassed over, so should your Coosa).

The Long Answer

If for some reason you would like to use a different thickness or install the material in a different fashion, there are a variety of things to consider such as:

  • What is the current span width between supports?
  • How is the material installed? (If glassed over, the fiberglass is adding additional rigidity)
  • Is the load spread over a panel or a point load?
  • How is the panel supposed at the edges? Is there a 1/2", 1"...6" overlap?
  • Does the panel need to support an impact load? (Think 300 lb guy jumping off a 5 ft. dock with an ice chest full of beer!
  • How is the board installed? Rigid bonded at the edges or free floating?
All of these factors need to be taken into consideration before a decision can be made on thickness. Boat builders pay a team of engineers to take all of these complex factors into consideration. We therefore recommend leveraging their decision and using the same thickness installed in the same fashion whenever possible.

If you are set on changing the thickness and installation method, please keep in mind that if you make changes that decrease the structural integrity of your deck you will need to make this up somehow. (i.e. if you choose not to fiberglass both sides of the floor, even though your original plywood was, perhaps you need to add additional braces of a stiffener to your span width).

How do I install Coosa Board?

Coosa Board can simply be installed as you would plywood or material being replaced using the same methods and tools.

How do I cut Coosa Board? Can you cut the board to my specific size and shape?

You can cut Coosa Board using any standard woodworking tools. Please make sure to take the same precautions (eye protection, gloves, dust mask, etc.) as you would when cutting plywood.

We are happy to cut your Coosa Board to any required size and shape. Please note that an engineering charge and/or a cut charge may apply depending on the shape of your pattern.

How do I use Coosa Board for decking?

You simply install the Coosa Board as you would plywood using the suggestions above. Many people have simply installed the Coosa Board and adhered carpet directly over the Coosa Board using their favorite adhesive.

Do I have to fiber-glass in the Coosa Board?

You do not have to fiber-glass in the board to prevent absorption of water/liquid; however, glassing the board also adds strength. Therefore, if you choose not to glass in (and your original decking was glassed), you will have to compensate for that loss of strength.

Is Coosa Board UV Stabilized?

Coosa Board is not UV Stabilized. With time, the boards will change color when exposed to sunlight. We recommend that Coosa Board be either glassed over, carpeted over, or painted with a latex or enamel paint.

What types of resin are compatible with Coosa Board?

All typical marine resins work with Coosa Board, including epoxy, vinyl ester and polyester resins.

I see elsewhere online a Nautical Coosa Board. What is the difference and is it available?

Bluewater Coosa Board contains continuous strand glass and woven roven fiberglass, while Nautical Coosa Board only contain continuous strand glass.

Therefore, Bluewater is significantly more rigid and is recommended for all structural applications. If your application is not structural (bulkhead, cabinet, etc.) then Nautical may be a good alternative and more cost effective than Bluewater. Boat Outfitters does not currently carry Nautical Coosa board; however, please let us know if you are interested as we always adjusting our inventoried material.

How does Coosa Board Ship?

It depends on the size piece you are ordering. If you order either a full sheet (96" x 48") or a half sheet (48" x 48"), it will have to ship freight. We are happy to get freight shipping quotes if you will send us your zip code and destination type (either commercial or residential). Please note that with freight shipping commercial addresses are significantly less expensive to ship to.

If you are ordering a third of a sheet (48" x 32"), then your piece can ship UPS. UPS shipping costs will vary based on location but will always be considerably less expensive than freight shipping.

Note: For the price conscious customer who needs a full sheet, please consider having your sheet cut into thirds. (3 pieces - 48" x 32"). This will allow your order to ship UPS and save you shipping costs.

When will my order ship?

Everything listed on the website is in stock available to ship. Our standard lead time is 2-3 days for Coosa Board.

Frequently Bought Together

  1. Coosa Composite Board - Bluewater 26
  2. +
  3. Stainless Steel T-Nut
  4. +
  5. Tuff Coat Medium Texture Deck Coating
Total price: $0.00
  • This item: Coosa Composite Board - Bluewater 26 $110.31

4.9 / 5.0
26 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
I havent cut it yet for my transom, however it is def sturdy amd just what i needed for the ultimate repair.
September 26, 2019
1 month ago
This stuff is great!
Light. Stiff. Easy to work with. Skillsaw goes right through it. Belt sander smoothes edges without melting plastic. If it weren’t for the cost, I’d use this everywhere.
User submitted image
Added Sep 16, 2019
September 16, 2019
1 month ago
Coosa board first look
I bought a small sheet, 1" thick of the coosa board for my aluminum boat transom repair. It is light and very solid. I was able to cut it down via my table saw and drill out the appropriate holes. So far seems to be very solid, though I haven't had a chance to test it with my 15HP motor, but hopefully will soon. I think this will work great for my project.
September 16, 2019
2 months ago
Great for transom repair
Coosa board worked great for the repair I needed to make. I’m so pleased I made the choice to replace the original wood with a composite since water seems to stay next to the transom due to poor drain location.
September 15, 2019
2 months ago
Bought it to replace seats in my small boat and the transom. The span on the seats was 32 inches. Original seats were three-quarter inch plywood. Coosa board definitely has more flex than three-quarter inch plywood I had to put braces under the seats. Overall product is good, no more rot. Painted to seal in fiberglass.
September 6, 2019
2 months ago
Great stuff
Easy to work with, made a rotted transom pretty easy to repair. Highly recommended!
User submitted image
User submitted image
August 27, 2019
2 months ago
Replacement of floor in storage compartment in my Motor Home RV!
I am so glad I was able to find the Boat Outfitters and the Coosa Composite Board. It met all my expectations and is very strong for the usage I need it for. I want to thank you all for your prompt shipping of this material. Yes, I would recommend this product!
This is of after I cut out the rotted floor.
This is the completed repair and replacement of the floor using the Coosa Composite Board!
July 31, 2019
3 months ago
Still working with it should be a lot stronger than wood easy to work with
July 18, 2019
3 months ago
And now for something different...
It also makes an excellent core material for fabricating a carbon fiber rifle stock. The stock chassis alone weighs in at 1lb 2oz. Entire rifle is 7lb 7oz with full magazine.
Build consists of:
Izhmash 7-2 Biathlon in 22LR
Sightron 4.5-14x AO scope
AAC Element suppressor

Stock was constructed using West System epoxy, 6k CF, Smooth-On expandable foam for the grip, Stretchalon bagging and a fridge compressor for a vacuum pump. Dremel & sandpaper to shape and a bit of epoxy automotive clear coat to give a nice orange peel finish. Whole project done on a folding table in the garage. It's a real critter gitter!
Carbon Fiber shell Coosa sections used to join butt stock and hex tube to main body of stock chassis
Coosa makes perfect reinforcement points for joints and insets
July 1, 2019
Highly recommended!
Great stuff ! Easy to cut. Lightweight to handle and glues solid. Completely waterproof!
June 24, 2019
4 months ago
Questions / Answers
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Browse 84 questions Browse 84 questions and 103 answers
Can this be used for a swim platform?
A shopper on Feb 1, 2018
BEST ANSWER: This material can be used for a swim platform, but it is a raw material. You will likely need to fiberglass the board for additional rigidity. If this isn't necessary, you will still need to cover the Coosa to protect users from the fiberglass in the material.
Is this being used in floors or aluminum boats in Half inch thickness or is it not rigid enough. Thank you
Brian earley on Jul 22, 2017
BEST ANSWER: Hello Brian, that is a great question. It is always recommended to use the same thickness as the plywood the Coosa would be replacing. If you are adding this floor from scratch the thickness needed would really depend on how it it is supported underneath. If you would like to discuss the specifics of your project please feel free to give us a call and we can go over some options for you.
I'm looking to replace the plywood transom on my 10' inflatable boat. Can Coosa board be used as a substitute? If so, what type of adhesive would be best ?
Bill Brousseau on Jul 21, 2017
BEST ANSWER: Coosa board is ideal for transoms, and most high end boat builders have gone to Coosa for the long term durability & weight savings.

It's very easy to work with (although you'll want some gloves and a mask because it does have fiberglass in the sheet). Alternatively, if you wanted to send us a template, we can cut a piece for you to the exact size/shape of your transom.

Regarding adhesives, I've linked directly to Coosa's recommended adhesive list -
I have a 1994 16' bass tracker and am considering replacing the floor and all other plywood, looking for my best long term option. what info would you need for an estimate?
Artie R on Jul 14, 2018
BEST ANSWER: Great question! Coosa is a great long-term alternative to plywood. Please give us a call to discuss the specifics of your project for a personalized quote.
I'm Replacing the aft center floor deck of my 1981 Ski Natique. The motor cover bolts to the deck via hinges. Is the coosa board going to resist the amount of pressure that could be applied there?
Shane A on May 20, 2018
BEST ANSWER: Great question Shane!
The Coosa Board doesn't quite stand up to standard screws the way wood does, so if you through-bolt the hinges instead of a standard screw you shouldn't have any issues with the Coosa Board.
I am replacing an old plywood firewall in my boat would coosa board be a good use for this?
MIkeG on Feb 10, 2018
BEST ANSWER: Great question. Coosa board would most likely be excellent in this application and we would love the opportunity to discuss the specifics with you on this. Please feel free to reach out to us for more information and get started.
I’m looking to replace a 1.5 in thick plywood transom on a late 70s Starcraft aluminum boat. Boat is rated to a 140 hp motor but transom is failing with 115 Yamaha 4stroke. Already replaced the transom about 15 years ago, so figuring I need to beef it up a bit. Was considering taking a piece of 1” ply and coating it with fiberglass. The splash tray is screwed to the inside of the transom and definitely adds some structural support. Would coosa board still have enough “screw hold” for this application. I would love to not have to do this project again. Any advice? Thanks.
Nordie on Jan 3, 2018
BEST ANSWER: Hello, Cossa is an excellent material for transom replacements it is typically recommended to us the same construction method and material thickness as what was originally used by the manufacturer. As for screw retention, Coosa does not hold screws, not quite as well as plywood but depending on the project there are some options available. If you would like to discuss your project please feel free to give us a call and we would be happy to talk through your options with you.
Can Coosa be scarfed similarly to plywood? I’m thinking about using Coosa as the outer layer of a cold-molded hull. I would need to scarf multiple sheets to achieve the necessary length.
KRIS W on Jul 29, 2019

Great Question!

Unfortunately, Coosa Board is not manufactured in a way for it to be scarfed. The material has several layers of fiberglass and composite material that would not allow the material to be easily planed out or chiseled.

Thanks Kris
what is the load carrying strength of a 48" x 47.5" x 1.5" thick sheet? Has the product been used for flooring on walkway for a floating dock?
Dudley B on Jul 6, 2019
BEST ANSWER: Hey Dudley, great question. The compressive strength of Coosa Bluewater 26 is as follows. .5" thick 800 psi, 1" thick 820 psi and 1.5" thick 1060 psi. Below is the link to the manufactures technical data. Please feel free to contact us with any other questions or concerns. Thanks!
how does it work mounting hardware? ie; grab rails? Looking at using it to replace sandwiched fiberglass rotten plywood deck.
Mark P on Apr 1, 2019
BEST ANSWER: Needs to be through bolted with nuts and washers. You can also use T nuts. Works very well as core material. Cuts best with diamond saw blades used for tile on 4 inch grinder or 7 1/2 circular saw. Will dull wood blades quickly tile blades will cut almost indefinitely. Wear a good mask you don’t want to breathe it eye goggles are also a good idea.
Can you get the coosa board custom cut to a specific size?
A shopper on Apr 1, 2018
BEST ANSWER: Great Question,

We can most certainly take care of that. You will need to give us a call in order to get this taken care of.

Can this be used to rebuild interior seats of a runabout boat - This would be covered with cushioning and then with vinyl. So, can you staple the vinyl to this and would it hold securely?
SCOTT T on Feb 25, 2018
BEST ANSWER: Great question Scott,

We suggest that you use Starlite instead of Cossa Board. Staples do not hold well in Cossa board and often will fall out.

Thank you Scott!
can coosa be cut into 2” wide strips and layered to make supports for a coosa deck?
A shopper on Jan 4, 2018
BEST ANSWER: This certainly sounds like something that can be done, but we could not tell you from experience. You will want to make sure to fiberglass all the way around the supports to get the full rigidity you are likely looking for. Thank you!
Can you drill and tap Coosa board to accept fasteners? Such as in the application of using it as a backing plate for a seacock flanges.
Sean D on Apr 8, 2019
BEST ANSWER: Hello, I used this material as a backer to 7 ply for a boat deck. The material can be drilled. Tapping this material will not work. the material does not have the density to allow for threads to be formed. It will just pull the fasteners out. My recommendation is to buy a sample and work with it.
I'm considering using this product for stringers, bulkheads and deck on my boat floor replacement. Since it won't hold screws well, how do you recommend adhering decking to coosa board stringers?
Trey G on Sep 15, 2019
BEST ANSWER: I used long screws to join 2 1" thick Coosa board for a toilet riser. No problem on staying fastened. There is Slkaflex 252 adheasive recommended by the manufacturer that is supposed to work real well. I would glue and screw it for max strength.
can you laminate 2 sheets of 3/4 inch coosa board together to make 1 1/2 inch and if so what do you glue it together with i.e fiberglass resin?
Truman A on Feb 28, 2019
BEST ANSWER: You can laminate coosa just like you would laminate wood or plywood. I have laminated 3/4 inch coosa to make a 1 1/ 2inch thikness in a transome. I would use a quality epoxy resin with a small amount of filler in it to glue the boards together.
I have a 1988 Bass Tracker and want to replace the 1" transom with the coosa board and cover it it with aluminum plate on the inside. I was thinking of adhering it with 5200. it has a 60hp motor. Will Coosa board work will for this fix?
Jonathan J on Feb 19, 2019
BEST ANSWER: I'd get thicker than 1" coosa board and then sandwich it between 2 aluminum plates. It's very rigid and waterproof . Then I'd drill and use stainless hardware to mount your 60 hp motor. That should handle the torque of your 60 hp motor and you won't have to worry about wood rot.Be sure to silicone any transom penetration throughly.
Being this is raw, and has a rough surface; can you sand the roughness out to paint or do you recommend a laminate instead; if not used in boat applications?
E M on Feb 12, 2019
BEST ANSWER: Coosa is fibrous. I do not think it will sand completely smooth. But, I like it much better in moisture environment then a laminate. What is your application you are considering using it in?
I am looking for something to replace the flooring on a 89 Four Winns 200 Horizon, would this be better then the fiberglass coated plywood that is on there now??
Steven W on Jul 27, 2019
BEST ANSWER: This is far better than plywood. But it wont hold screws very well. Must be through bolted to mount hardware or use tee nuts and machine screws. Cuts best with dry cutting tile blade, I use a 4 inch on grinder and 71/4 inch on skill saw, will cut like butter. Wear a mask. I would also use epoxy resin and appropriate glass cloth. Glass bottom before adhering to stringers. Then glass top and up hull sides and you will never have a soggy floor again.
do holes drilled in coosa board have to be sealed to keep water out ?
jason k on May 11, 2019
BEST ANSWER: Hi Jason, coosa board does not absorb water and does not rot, so your holes don't necessarily need to be sealed. In my personal opinion, sealant can help hold fasteners in place and it still a good idea anyway because of this.
I’m looking at fabricating my own swim deck platform. What thickness would you recommend?
Seth J on May 5, 2019
BEST ANSWER: Hi Seth, Great Question!! Typically our swim platform thicknesses are in 3/4" starboard. I attached a link for you to check out the King Starboard product on our website. This is also available in Anti Skid as well which would be a nice feature for a swim platform as it would provide some grip when getting out of the water.
Good morning, I have a 86 WELLCRAFT V20 CC, that I have to replace the transom. I was told by other owners of this same boat, that that WELLCRAFT made the transom out of three sheets of plywood that is angled slightly, And most use seacast instead. Will the cosa board work for this project? Thanks
Francisco V on Apr 26, 2019
BEST ANSWER: I believe it should work, you may have to buy the thinner boards and laminate them together in order to make the angle or curve...not sure how much flex they would have. I used 1/2 inch to recore a deck hatch.
Have a 16ft aluminum boat with fold up seats in it can I use the boards for the floor of the boat to bolt the seats to??
Keith K on Apr 19, 2019
BEST ANSWER: Yes, I believe that if you use one of the thicker Coosa boards with bolts and large Diameter washers on the back side to distribute the weight, it would work great. Coosa board is light but very strong and will not rot nor mold. You might also consider a couple of layers of fiberglass on the bottom side of the Coosa board to help distribute the weight. Coosa board is so easy to work with.
Thinking this would make a good backing plate for seacock flanges? 1/2 or 3/4 inch? Hull is solid layed up fiberglass about 3/4 inch. Want to never have to do it again
Sean D on Apr 8, 2019
BEST ANSWER: I used Coosa recently on a boat rebuild—it can appear to crush when overly compressed and then the lack of ‘fiber’ in it (vs plywood) leaves it a bit loose to bolt into. That said, if you use the 3/4 and can bolt all the way thru it with some solid washers on the back you should be fine. I found Coosa very easy to work with and bond to with fiberglass and the ‘never-rot’ characteristic is extremely welcome.
Can this be used as a stand alone transom product, say on a houseboat with steel pontoons?
Dan J on Apr 2, 2019
BEST ANSWER: i don’t see why not. as long as its laminated to a proper thickness and attached to your pontoons properly
I have a 79 model fiberglass boat and would like to replace deck lids for storage compartment, and carpet it. What thickness do you suggest for a 2lt x3ft lid? And the guy standing on its 300lbs
John A on Mar 24, 2019
BEST ANSWER: 3/4" would work with out any doubt, 1/2" would work as well but since there's not much weight difference I would go with 3/4" and never look back
I have a 1983 bass tracker ll need to replace transom can buy it to fit my boss?
George on Feb 28, 2019
BEST ANSWER: I rebuilt my transom in a 96 aluminum bass boat with coosa board. I bought a 4’x 8’ x 1/2” sheet, used my old transom to trace the outline. I cut three pieces to make it a 1 1/2 “ thick. I went a little overboard and sandwiched 1/8” aluminum in between the three peices of coosa and cut a 1/2” piece of aluminum for the rear of the transom this gave me the same thickness of the transom i was replacing, but much stronger than the plywood that was in there in case i want a bigger engine in the future and it will last longer than the boat.
Can Coosa bend on a slightly curved transom ?
Jeffrey M on Feb 18, 2019
BEST ANSWER: I dont see how unless you bought a thick piece and carved out what you needed to make it fit. It's very stiff and will not bend that I can tell.
Hi I have and older sylvan aluminum boat that needs a transom replacement and I understand you can cut coosa board in shop for me? If I gave you the vin numbers could you pull the demmensions and cut it for me?
Andrew C on Oct 8, 2019
BEST ANSWER: Andrew - Great question! We can definitely help you with your transom replacement if you provide the dimensions of your transom. More complex transom replacements might require you to send a template. If you give us a call at 866-633-7961 we'd be happy to assist!
using as bench seating, needs to be UV paint protected. what paint to use?
Rick S on Aug 17, 2019
BEST ANSWER: I wouldn't use Coosa unless it is well braced from underneath. It will need to be thoroughly sanded because it is very rough to the touch. After sanding and bracing I would go to a reputable paint store like Sherwin-Williams in there ask them. I would think they would recommend an oriole-based payment rather than late text.
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