Bass Relief- A Seafari 25 rehab

[FishStretcher]

I hate grinding. I think I spent 5-6 hours with a 4-1/2 inch angle grinder with 40 grit flap wheel. And I got something (fiberglass, of course) in my eye, despite the glasses and the moon suit. Looks like nothing major, thankfully. And I look like I went to a paintball gun fight wearing nothing but jeans and a t-shirt. Little circular bruises everywhere. Laying on stringers all weekend will do that to you.

I slipped with the angle grinder and went thru the tabbing into the first layer of woven roving on a stringer. Nothing big, but I will patch it up. Thankfully, the stringer tabbing looks ok. I think this boat was a trailer queen, and damage is from storage, not flying off waves.

Then I grit blasted some. That is very effective. But I had to level out the surfaces for the foam spacers first. What a PITA. But it looks good now.

I also got the carbon fiber deck stiffener laid up. I managed to put a 3/16" crown in it (the right way!) for better deck runoff.

I may add one more bulkhead forward- or at least prep while I am in there- maybe CF over foam, as I forgot I has so much cloth laying around. Then I have to hustle to get this done before July 4.

[Normagain]

I'm curious how effective the blasting deal is from HF? Was thinking about getting one of those for a project coming up soon.

Also, how the carbon fiber works for stiffening. I've been playing around with cloth/epoxy on a scrap piece of 1/2" Coosa to see how stiff it gets when laminating both sides. It does work pretty well but I think carbon fiber might be a good way to go despite the extra expense.

The boat looks like it's coming along great!

[FishStretcher]

I got the small one. If I wasn't throwing it over a gunwale 6 feet off the ground, I would rather have gotten a large one for extra capacity. And get black beauty somewhere a lot cheaper than there. Like $0.25/lb, not $1 a lb.

Once I adjusted the media flow down, it worked great.

The carbon is stiff, and lighter than glass. But for what I am doing, I could have purchased a better glass orientation. (My 20 year old carbon cloth was free to me). I had a first layer of 1708DBM. So the fibers are at +/-45 degrees. Then two light layers of carbon in a 2x2 weave (I think), having a lot of roving running longitudinally along the stiffener- the most advantageous orientation for me. So it is quite effective. And light. But 1708DBM, then uni glass, then a biax cap would be pretty good, I imagine. Not quite as stiff or light, but way cheaper if I had to buy reinforcement. Again, I got my carbon for free, so that's why I used it there.

There are galvanic issues with carbon, so I only put it places where I won't screw into it. I believe it eats aluminum for lunch- worse than stainless.

And for the doubters in the bunch- the vinylester/ biax I put in last year was a LOT harder to remove and far more impact resistant than the original poly/glass. I was trying to break tabbing with a 4 lb hammer and getting nowhere on the vinylester. The polyester and glass broke pretty easily. It seems vinylester(epoxy) really does have a lot of elongation like ordinary epoxy.

[Normagain]

I didn't know about the galvanic issues with carbon fiber. It looks like people do use stainless fasteners so I wonder what the longevity is. If it's a 10 year thing rather than say 5, I can live with that. My plan was to do one layer of fiber cloth and then regular glass over that. Same on both sides so point of contact would be minimal between fasteners and carbon cloth. I know where the deck fasteners will be so could just do a cutout in those areas to be safe!

[cdavisdb]

Nice Job, FishStretcher. Your pics of the bulkheads coming out bring back a bunch of "less than pleasant" memories. I can feel your pain. Great that the tabbing looks ok.

Where do you plan to put your extra bulkhead? It needs one for sure forward of the forward tank bulkhead.

Connor

[FishStretcher]

Originally Posted by cdavisdb

Nice Job, FishStretcher. Your pics of the bulkheads coming out bring back a bunch of "less than pleasant" memories. I can feel your pain. Great that the tabbing looks ok.

Where do you plan to put your extra bulkhead? It needs one for sure forward of the forward tank bulkhead.

Connor

Practicality and timing will dictate this to a degree, but I intend to put it forward of the forward tank/cockpit sole bulkhead. If I have the time, I hope to put the foam trapezoids in after I gritblast a clean spot. I might lay a layer of 1708 over them with peel ply and leave the peel ply. If I get a bulkhead cut out in time, I will install it, else I leave the peel down. It will likely be in an area that I can reach from the two false bottom lockers under the bunks. Reach from both sides for installing the tabbing. One false bottom is yet to be created. The port side exists.

That way I can install and tab at my leisure. At least with respect to schedule, if not comfort.

It will be a low half bulkhead, not all the way to the cabin floor, I think. (I haven't measured yet.) But enough to keep the stringers from collapsing inward from slamming loads. I hope.

[FishStretcher]

Originally Posted by Normagain

I didn't know about the galvanic issues with carbon fiber. It looks like people do use stainless fasteners so I wonder what the longevity is. If it's a 10 year thing rather than say 5, I can live with that. My plan was to do one layer of fiber cloth and then regular glass over that. Same on both sides so point of contact would be minimal between fasteners and carbon cloth. I know where the deck fasteners will be so could just do a cutout in those areas to be safe!

It is more of an issue with aluminum, as far as I know. But in a saltwater environment, it looks like even stainless will have a hard time?

http://en.wikipedia.org/wiki/Galvanic_series
http://en.wikipedia.org/wiki/Galvanic_corrosion

"Hard points" are often epoxy encapsulated for this reason on graphite composite structures. Kind of a PITA.

Cutouts in the cloth is one way to do it, I suppose. Or potting the joint so there isn't contact?

[gofastsandman]

Originally Posted by FishStretcher

Practicality and timing will dictate this to a degree, but I intend to put it forward of the forward tank/cockpit sole bulkhead. If I have the time, I hope to put the foam trapezoids in after I gritblast a clean spot. I might lay a layer of 1708 over them with peel ply and leave the peel ply. If I get a bulkhead cut out in time, I will install it, else I leave the peel down. It will likely be in an area that I can reach from the two false bottom lockers under the bunks. Reach from both sides for installing the tabbing. One false bottom is yet to be created. The port side exists.

That way I can install and tab at my leisure. At least with respect to schedule, if not comfort.

It will be a low half bulkhead, not all the way to the cabin floor, I think. (I haven't measured yet.) But enough to keep the stringers from collapsing inward from slamming loads. I hope.

Clarity is good. Are there any concerns with the differing flexural characteristics of CF and glass?

[FishStretcher]

The stiffness of the CF means that it takes the stress much faster than the glass for a given load. Plus the fiber orientation means it would do that, too. The biax will help spread the load well across the flange and into the bottom skin of the deck. I think.

The 4-5% elongation of the vinylester epoxy matches the glass well. The carbon will break long before that. But that's fine. If I ever get that far, then I will have a springy deck with broken CF, but likely some intact biax for a little while. I suspect that would be coming off a heck of a wave and slamming with a giant BFT on the deck. The CF isn't really lots stronger than the glass, but lots stiffer, and lighter, so it is very efficient.

I really want to put a layer of biax/vinylester in the hull between the stringers, but I don't have the time or resin. That stuff is so tough, it would be a great as a last line of defense against punching thru the hull. Oh well.

[FishStretcher]

I think I am done grinding. And sandblasting. Sandblasting is great. It doesn't flatten anything out, but it roughs it up instantly. I went through 160lb of coal slag (black beauty) today. I think I spent 90 minutes vacuuming out the hull, though. This is really slow going.