Keel tank construction

[shufti]

What about a fuel bladder rather than a solid tank?

[Uncle Bob]

Originally Posted by GILow

I was surprised too. The story came out because I called the original main owner after doing some work on the interior and getting really worried about the smell. It did not smell like polyester at all.

He explained the weird history of the boat. It was not build by the Swanson Brothers because the bloke who commissioned it wanted the hull thicker (much thicker) than normal and the Swanson Brothers (correctly) said that was silly and wouldn't do it.

So later, when they were hiring out the molds to home builders, he hired the mold and had a Sydney boat builder lay up the hull with and extra ton of resin and fibreglass. Yes, a ton. It is believed that he had it laid up in vinyl ester. (and it smells like it too, quite different to normal polyester, whatever it is.) He spent so much money on the hull he could not afford to even put a deck on it, so sold the hull to two brothers who did the initial fitout, before they had a falling out and sold it, 75% complete, to the main owner, who is the guy I have been in touch with and got the full boat history. He sailed it for 42,000 miles through the South Pacific so has been a great help. He also added a further ton of ballast, so she's about two tons over weight. Makes for a nice smooth ride, but not great in light winds.

No osmosis. That's a nice thing.

Now I understand why you are so sure that the hull will not flex.

[GILow]

Originally Posted by Fore and Aft

That’s why I am not keen on built in tanks. I have surveyed a few boats that have had osmosis inside and outside their tanks. One yacht that sticks in my mind had like a line of osmosis where the tank started and finished.
I cannot see any reason why you cannot line the keel area with a couple of layers of chopstrand/vinylester and put a lid on it for a fuel tank.
Cheers

So... not sure what you are saying here...

Are you saying the chopstrand/vinylester is a GOOD idea? Or do you think there will be an osmosis problem if I do that?

[GILow]

Originally Posted by shufti

What about a fuel bladder rather than a solid tank?

Some of the same problems apply. I.e. I would need three separate bladders, and they are not cheap, at least in terms of my budget.

I also had a HORRIBLE time removing a hardened bladder tank from the keel tank under the engine, without doubt the worst job I have ever done on a boat, and I include fixing a friend's toilet plumbing in that list.

[GILow]

Originally Posted by Uncle Bob

Now I understand why you are so sure that the hull will not flex.

Yeah, not a lot of concern. But, in fairness, I am still reluctant to remove those bulkheads in the keel. I mean, it SHOULD be ok... but who knows...?

But seriously, it's all dead weight really. The Swanson 42 hulls were rock solid the way the Swanson Brothers built them, this sort of over engineering did nothing except drive one guy to financial ruin, and leaves me lugging an extra ton of pointless weight around the ocean.

[Fore and Aft]

GILow, I was really meaning you should line the bilge area with two layers of chopstrand mat and vinylester. I am not sure I would fully believe the vinylester story unless I was there on the day they were laying up the hull......Besides I am not sure how porous ester resins are after 20+ years. I assume those bulkheads are going to become baffles so I would want to be 200% sure that they are sealed. In particular where ever you drill holes to allow the fuel to pass through.
Cheers

[GILow]

Thanks for that. Yes, I got a similar approach recommended by a resins enthusiast/professional on boat design. They recommended painting the area with a couple of coats of VE first then the mat. Sounds logical to me.