progress on ripping up floor and new tanks on the shark cat.

[lembo]

so the sharkcat has a leaky tank, I decided to bite the bullet and rip up the floor and get some new tanks, replace some rotted timber and give it a nice new floor.
So after flushing the old tanks 3 times to avoid blowing my head off (if I make sparks) I attacked it with my grinder and got the tanks out. and to my surprise after the old owner told me they were 120 litres each I worked out they went about 175 litres.
they had a bit of fibreglass ontop holding them in place.
So with the explosion danger gone I got stuck into pulling up floor and cutting out under those bloody side pockets! (real pain ).
Man these things are built solid, floor was solid glass same as bulkheads which are every 600mm, which have timber crossbeams and uprights glassed to them and in between every bulkhead a crossbeam with an upright. Way stronger built then my old kevlacat.

So heres the plans of what im going to do, hopefully its ok as its my first time glassing.
Im cutting out all timbers and replacing them with a product called coosa 26 cut into 75mm wide strips and polyester resin. glassing them to all bulkheads and side of boat.
Moving front fuel compartment bulkhead forward to sneak in slightly larger fuel tanks.
putting down a ply floor fully glassed both sides then glassed into boat.
only going to have two spin out hatches to access back two compartments .and some flow coat underfloor and on floor to tidy things up.

is polyester glass ok to use for this job ? was going to use epoxy but local fibreglasser told me just use polyester?
And what other ply replacement products are out there ?
110266
leaky tank out
110267
how tank was secured
110268
couple rotten timbers
110269
both tanks out and working around under side pocket to get last bit of floor out.
Any help and info on things would be helpful.

[Oceanic Dave]

How did you find out you had a leaky tank?

looks like a lot of work, good luck! Looking forward to the finished product!

[Noelm]

Pretty typical of how all Sharkcats are made, just be careful moving the tanks forward, most of that model had 180l or 205l tanks, make sure the cross over beams are OK and glassed in well, not exactly sure of what you are doing from your description, but they are a simple and strong build, so as such, pretty easy to work on, cutting under the side pockets is a pain for sure.

[lembo]

yeah there built solid, wouldn't say pretty but solid. the bulkhead at the front of the fuel tank will be moved forward about 200mm. I found out one tank was leaky as I have inspection ports into each compartment and when I opened up one of the fuel tank ones it had a strong smell of fuel. the tank hole is tiny (cant even find it) but its there and definitely leaky.
Has anybody used the product coosa 26 ?
it looks great but pretty pricey. any other timber replacement products you guys can recommend ?
Or should I just stick to marine ply fully glassed ?

[Noelm]

Marine ply will be heaps better than what was in there from new, most of the timber is plain old hardwood, and not fully glassed, some had pieces of Meranti here and there, but all in all, pretty rough.

[Darren Mc]

I'm pretty sure Bonito Boats use coosa in there hulls. Pretty good product i'm sure and no rott.

[Master4Med2]

Lembo, are you replacing everything under the deck, such as bulkheads and cross-over beams ?
Your not touching the transoms, are you ?

[lembo]

No transoms not getting touched, its the most solid transom ive ever seen. only bulkheads im touching are the 2 at the front of each fuel tank compartment, whick im cutting out and re glassing a couple hundred mm further forward bulkheads are full glass and have no ply in them. im cutting all cross over beams out including ones that are glassed to top of bulkheads, and all upright timbers. there is an upright glassed to every bulkhead and one on the crossover beams that are between bulkheads. I will be replacing the uprights that are glassed to the bulkheads but not the ones in between bulkheads. and also replacing the timber that's glassed all around the edge of the boat just under the floor.
Im considering just using marine ply for everything with 2 layers of glass to seal it.
yeah Noelm it had hardwood crossover beams that weren't fully glassed. theres a fair bit of the hardwood that is deteriorated to a soft crumbly mess.
Do you think the ply would have enough strength to use as cross over beams if cut into 75mm widths ?
I might save myself quiet a bit of money using marine ply instead of coosa 26, still weighing it up.

[Master4Med2]

Lembo, since your not doing a complete refit under the deck, I would use plywood.
For the bulkheads, 19mm plywood will do the job. As for the cross-over beams, mine are a thickness of 25mm, so I would laminate two layers of 12mm plywood together for them.
One thing I would change is to use honeycomb for the deck instead of plywood.
Using 25mm honeycomb with two layers of 600gr +/-45 Double Bias will weigh about a third of a plywood deck.
With the plywood bulkheads and cross-over beams you can glass them in with two layers 450gr +/-45 Double Bias.
Use epoxy for everything, with any plywood not glassed, use two coats of epoxy.
Honeycomb will be cheaper than plywood.
Did you price Coosa, 19mm is over $400.00 a sheet, great stuff to use but over kill for what your doing.

[FisHard]

I believe Signature use Coosa in their transoms now.

[lembo]

Thanks master4med2, yeah the plan was to glass 2x12mm together for the cross over beams.
Yeah that coosa is very pricey, so you think epoxy hey. I was originally going to use epoxy as ive heard it has much better bonding strength, but then my local fibreglasser said use polyester as that's what my whole boats made from so why change. So im a little confused at which one to use.
If I went epoxy for everything what product goes over the top of it to finish it off ? does a flow coat go over it?
Sorry if questions sound silly but im a novice and and trying to educate myself.
So what is this honeycomb product made of ? sounds good. ? I might call up composite place Monday and ask about it.
Thanks for everyones help much appreciated.
Master4med2 how is your boat going ? have you got the pods built yet ?

[Master4Med2]

Lembo, I've sent you a private message.