Hey! Now we're talking. I can use SikaFlex 291 to put UHMW (thin) on the
bottom of the hull or whatever support stringers I put in (removable), then
use 3M 5200 to put UHMW strips on the bottom of the tank (permanent). No
water can gather between the tank and the support materials, nor between the
support materials and the epoxy/glass/wood either, and the UHMW will prevent
chafing forever...

Thanks for the inspiration ...I think I have a solution: custom tank, and
artful use of UHMW and supports!

Brian


"Dave Cannell" wrote in message
.. .
Brian,

Something a tank builder in RI suggested to me was mounting the tank on
something like UHMW material attached to the tank with 5200. That way no
water can get between the mounting device (UHMW pad) and the Al tank.
That would take care of keeping the tank from going any lower (gravity
again) and I guess straps across the top, but there you go again with a
water entrapment problem. Maybe more UHMW pads and a strap over them?

I'm leaning more and more toward a plastic tank, looking for a small one
but it has to fit under the cockpit and behind the mizzen step of o my
Kenner Privateer 26, a bit over 10 gals would keep me quite happy.

And I found out just the other day that Todd no longer makes the small
tanks, apparently only larger ones.

Do the makers (Tempo and who else) put baffles inside these plastic tanks?

Dave Cannell
--
In article %L4kb.805694$Ho3.219150@sccrnsc03, Brian D wrote:
We have a local guy here that teaches welding at the college and he's a
persnickety perfectionist and very very knowlegible about all types of
welding. I know another guy up in Homer, Alaska that is also extremely
top-notch and an excellent welder. I'll do my homework with both these
guys
on the tank design, and then will spec it out. I'm hoping the local
college
guy will weld it up for me ...he's such a perfectionist, not just with
the
welding but all the structural issues. His students pass the
certifications
at very near the 100% level, one of the highest rates of successful
certifications in the country. I don't know if he's willing to do
custom
work but I sure hope so. I just want to get all the answers I can
before I
go chase him down.

Having the tank suspended by the longitudinals means free open air under
the
tank and prevents corrosion. I guess I could put a support stringer
under
the tank and weld on a sacrificial strip of aluminum that'll rest on it.
Something like 1/4" thick...take a few lifetimes to corrode that away,
assuming you seal-weld the edges and don't trap water between it and the
tank via capillary action. Education is ongoing ...I'll keep looking
into
this stuff. And I *do* own the full set of ABYC and USCG specs ...need
to
go read the fuel tank stuff too.

Dave Gerr has a couple of articles, a 2 part series, in the current
Professional Boatbuilder and the last one (Number 84 and 85,
August/September issue and October/November issue, 2003).

Brian