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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
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  5. Tuff Coat Medium Texture Deck Coating
Total price: $0.00
  • This item: Coosa Composite Board - Bluewater 26 $110.31

5.0 / 5.0
15 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Best product for the money and job
Love it, way better than plywood and a lot lighter, don’t plan on selling the boat, so this will last lot longer and don’t have to worry about again.
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May 20, 2019
4 weeks ago
I have not used it yet but it looks like really good stuff
May 16, 2019
1 month ago
Great stuff
I used the 1 1/2 inch coosa board to rebuild the transom on my 17' lund. The board really made the job go quicker because I didn't have to bother with glueing plywood to gather to make the new trasom board. Didn't have to coat the coosa board with anything to keep water from soakin into it. It was lighter than plywood and just as ridged if not more so. Coosa board was very easy to cut and work with. It is kind of pricy but probably worth it in the long run because I'll never have to worry about it rotting. I highly recommend it.
April 23, 2019
1 month ago
Great for decking and transom replacement
Used recently in a Glastron Carlson 16CVX rebuild—very easy to work with and to create long lasting floors/transom. Note: my floor was so narrow in that boat that it had no stringers under the floor just the keel for support—I installed 1/2” Coosa and I found it flexed under foot more than I liked so I would recommend 3/4” for flooring (or be prepared to build a few supporting stringers, which was my solution—floor works fine.)
Transom and supports are 1 1/2” Coosa (more fiberglass matting added after this photo)
Keel is 1/2” Coosa 3 layes sandwiched and wrapped in fiberglass—stringers added
Floor 1/2” Coosa—very easy to shape and fiberglass in (photo before glassing in)
April 9, 2019
8 months ago
Top quality product
Rope locker
New storage cabinets
April 5, 2019
1 year ago
Great product, and great service!
First time using Coosa board. I like this product! Easy to machine and work with. Will order again.
Fast delivery as well.
March 18, 2019
3 months ago
Impressive product, easy to work with
So far so good. This 24' Sundancer pontoon from 1991 had a plywood transom that was beginning to rot on the bottom where it had the most contact with water. I had to have the motor rebuilt this winter so it was the perfect opportunity to also replace the damaged transom. I purchased a 1/3 sheet of the coosa 26 bluewater after a couple calls to the nice folks at boatoutfitters to ensure that this was a good application for the board. They insisted that this is an ideal application. My old transom was 1 7/8" thick so I bought a 1" thick sheet of coosa, cut out two pieces to match the old transom by tracing the old piece and I cut them out using a 6.5" cordless circular saw. Per the recommendation of the agents at boatoutfitters I purchased a sheet of fiberglass cloth and resin (i used a bondo kit from the hardware store for $12) I cut the cloth about 1/2 smaller than my pieces of coosa, coated one panel with resin, layed down the cloth then saturated it with resin. Next I coated the opposite piece of coosa with resin and sandwiched the pieces together. I placed the group flat and put weights on them overnight. The next night I coated the entire piece with resin and let dry. Once dry it was time to try installing the board. Lining up the mounting holes (with compound angles) was a challenge, but I figured it out by drilling the top holes by eye then I marked the remaining holes with my drill bit with only the top two bolts inserted into the mounting brackets. I then removed the bolts and board and used the angles in the old transom as a guide (the original board had to be slid off the edge so the holes would line up properly, but the drill bit would maintain the original angles and placement) this method got me super close and required only minimal drilling to ensure the bolts would line up. The last part was fitting the top cap. Because I now had a full 2" transom and the original was only 1 7"8 I had to trim a small amount from the top face of the new board using the table saw and I rounded the edges with a file. The end result is pretty fantastic. The board was very easy to cut and drill. Everything is through bolted and the motor mounts are backed with a thin piece of stainless. I hope this is the last transom I ever have to put on this boat and I am very anxious to get it back in the water with the fresh parts and motor!
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March 7, 2019
3 months ago
Review sent in previous email.
New Coosa board transom
Old rotted plywood transom
January 30, 2019
4 months ago
Great product
Rebuilt the transom on a Lowes pontoon.
Coosa board was a pleasure to work with.
Highly recommend it.
November 23, 2018
7 months ago
Coosa sandwich
Absolutely love it! Used in place of plywood for a transom on my aluminum boat. Sandwiched it between 2 pieces of 1/8th inch aluminum plate and bolted it in. Stronger and lighter than anything I've ever seen used, easy to work and practically bulletproof when sandwiched!
September 13, 2018
9 months ago
Questions / Answers
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Browse 72 questions Browse 72 questions and 89 answers
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 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.
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.
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.
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.
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.
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.
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?
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.
Can I use this as decking for my 21' pontoon boat?
j m on May 7, 2019
BEST ANSWER: Absolutely, on the long run it will prove to be a great investment. Lighter and stronger. Suggest 5/8 or thicker.
I have a 03 malibu sunsetter and my in-flr ski storage locker floor panel door is only 3/8 thick by 10"x 42" so my questions are 1. I saw the thinnest you show available is 1/2 in. can I order it in 3/8 and if not can the coosa be planned down? 2. do you think it would be structurally sound at those dimensions. thanks
mark w on Mar 22, 2019
BEST ANSWER: I wouldn't plane it fiberglass shards are dangerous to your health. Also 10" x 42" is a long thin piece. Most boats use extruded aluminum for those applications
I am replacing the half inch thick plywood flooring in my motorhome that is screwed down to metal floor joists if I use your coorsa board do I screw it down also and can I glue a laminate flooring to it?
Frederick R on Mar 3, 2019
BEST ANSWER: Hi Frederick,

Great Question! You can use Coosa board just like you would plywood. Screwing it down to the metal floor joists would be no problem. You can use adhesives on the board as well so gluing down laminate floor to should be no problem.
When will you sell products in a 1x4 or 1x6 ?
Steveo on Feb 17, 2019
BEST ANSWER: Hi Steve, If you contact us on our contact page, we will better be able to answer your questions.
Does it contain any VOCs? I’d like to use this to replace the plywood flooring in my 1971 Airstream. Additionally, I’d also like to build wall partitions for a shower, bunk beds, kitchen, etc. Your thoughts on this and any recommendations for finishes to prevent fiberglass fibers piercing the family would be greatly appreciated.
John M on Jan 31, 2019
BEST ANSWER: I don't know about official VOC numbers, but there was no odor and no indication of any VOCs when I received. The boards are lighter in weight and stiffer than standard plywood. There is no moisture or wetness they are completely dry with no smell. Any kind of paint should work, but you will need several coats as the surface has some texture. Handle with gloves to avoid the fiberglass itch, until you get a primer coat on it then it should be fine. It cut with a circular saw the same as wood does, only a little dust.
I own a 204 grady walkaround. It has a 175hp Johnson on it now. Transom is shot. I want to repower it with (2)100-115hp outboards. What thickness coosa board should I use or should I sandwitch (2) 3/4” pieces together? Thanks
Gator on Jan 25, 2019
BEST ANSWER: if the transom was laminated 3/4 plywood , I would use the same lamination of coosa to replace it. it Is easily as strong as the original plywood but remember that it will not hold screws as well as the plywood.
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