Shaping a wedge out of Coosa board

[Ostinato]

I have a sugar scoop step on a cat that is literally acting as a scoop and holding water. It was built incorrectly at the factory. The step on the other side sheds water correctly.

To fix this I need to fill the step with a wedge that is fairly light but has compression strength because people will be stepping on it. I expect to cover the wedge with fake teak for cosmetic and non-skid purposes. (The other side will be covered to match.)

Coosa board has been recommended to me by several people but no one I spoken to has any experience sanding it into this kind of form. The concern I have is sanding through the embedded fiberglass.

Another alternative is Airex PXc board but it also has embedded fiberglass.

The photo shows the scoop with a small amount of water in it. Normally the water goes right to stern edge of the step.

The step is 26" deep and 40' wide. To the get water to flow off the forward edge of the step needs to be raised at least 1" and tapered to virtually zero at the stern edge. Usually the steps fills with water whenever my cat in under power at cruising speed and, of course, under sail in a following sea.

Does anyone have experience sanding through the embedded fiberglass in Coosa board and how difficult was it?

[psk125]

If you’re planning to cover it with teak anyway, why not use epoxy filler after sanding the step a bit to ensure it all stays put?

[Ostinato]

Too much weight. Plus you need special epoxy for filling a space that big. West isn’t good for that kind of application unless you layer it as I understand it. There are some other strings on this technique.

[Wind River]

Coosa sands easily. You will not even notice the glass while sanding except when you start itching from it. Cover up while sanding.

[Franziska]

You can use epoxy. Use slow hardener and a light-weight filler. Make sure the ambient temperature is not to high.
Add some short strand glass fibers to the mix as well to avoid cracking.

If you feel you have to much volume, use a marine plywood plate shape it and laminate over it.
Paint it and you are done.
Good luck!

[Nicholson58]

Use US Composite 635 THIN Epoxy resin heavily filled with 3M micro balloons. I used this to fill my rudder 5 inches thick. See my photo album. The mix will pour and level out. It can be sanded, faired, painted. It is totally waterproof.

Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc.

[Ostinato]

Originally Posted by Wind River

Coosa sands easily. You will not even notice the glass while sanding except when you start itching from it. Cover up while sanding.

Thanks, that is exactly what I needed to know.

The idea of flooding the area with a self-leveling epoxy seems attractive except for several factors. The most important of which is that I have angle the step's surface so water runs off like in a shower when our cat is sitting still. The boat is on the hard now which is the best place to do this because I don't have to deal with wakes or waves unexpectedly splashing on the surface. But it also means I am not sure if the boat is sitting the same way it would be if it was in the water (bow to aft or side to side).

Micro balloons do absorb water according to West though I doubt it would be much of a factor in this application.

Wood is an option except for weight and that this area will still be awash while underway. My experience with wood - especially plywood in this kind of environment - is not the best.

[captain465]

Why not just create a drain from the low spot through to the hull? The photo shows it to be a short distance, and the overboard rain would be above the waterline. Way less work and not too hard to DIY.

[Pendragon35]

Boatworks Today had a whole series on using coosa https://www.boatworkstoday.com/video...esson-learned/

[Ostinato]

Now that’s a thought. The intake would have to be flush. The biggest problem would be channeling all the water to it. The water usually seems to pretty evenly distributed usually though in the picture it is pooling on the port side. But it would take care of most of it and would be very inexpensive. If it didn’t work well enough I could still build it up. Hmmm.- interesting idea.

[Bill O]

Originally Posted by Ostinato

Does anyone have experience sanding through the embedded fiberglass in Coosa board and how difficult was it?

We made a whole replacement rudder with Coosa. We routered it to get the main shape, then came back and finished sanding it for the final shape. The router cuts made contour lines to make the final shaping easier.
It does create a lot of dust, so us proper protection. I used a better dust respirators (not the paper ones) and tried to be fully gowned to keep the dust off me. Having someone follow the router w/a powerful shopvac (W/gortex dust filter) w/helpful.
Besides the dust, it is really great stuff to work with and glasses easily.

Bill O.

[Ostinato]

Originally Posted by Pendragon35

Boatworks Today had a whole series on using coosa https://www.boatworkstoday.com/video...esson-learned/

Thanks for the link. I just viewed the first video and it is very helpful.


Bill O - that looks like a well done job. Wish I had known about this stuff years ago when I replaced a rudder.

[Cadence]

Are you sure redistributing your weight, in that hull, won't solve it?

[SwellGuy]

I must be misunderstanding something.

Isn't worrying about the weight of this tiny repair pointless when a coffee mug left next to a berth is likely to have as much impact?

Hope all your tanks exist in a single point at the center of mass of your vessel, otherwise you'll really be wasting your time!

[thunderhoof]

Could you temporarily have the boat on the hard trimmed bow down just enough so if the step were flooded with epoxy and then cured level it would have enough slope to shed water after the boat is refloated? I think you could use a filler to reduce weight in most of the epoxy and add on or cast in non-skid on the surface.