[Public-List] gas tank replacement

[Gordon Laco]

Hello Stephen - 

Great description of your job - I'll print and keep it.

Thanks,

Gord #426 Surprise


On 18/07/13 4:32 PM, "Stephen Gwyn" <stephen.gwyn at nrc-cnrc.gc.ca> wrote:

> 
> 
> So this is going go a bit long.
> 
> I replaced my tank a few years ago. The tank I removed was not
> original, so it's unlikely to be the same dimensions as yours.
> 
> I measured the tank several times and concluded that there was no
> way it was going to come out with the engine in place. I made a
> cardboard template of the end of the tank and tried angling it
> different ways. No chance. Since I didn't want to remove the
> engine, I went sideways.
> 
> I removed the plywood bulkhead between the engine compartment and
> the port locker. This is a lot less work than you think it might
> be. There are a few fasteners, a mixture of screws and pop rivets
> but they were easily removed. The bond between the fibreglass
> deck molding and the plywood bulkhead had long since
> deteriorated. Wood almost always ends up separating from glass
> because they expand differently with temperature and moisture
> changes. I used the curved end of a thin crowbar to gently tweek
> the few remaining sections where the bond was still almost good.
> 
> The main problem was I did this in a Pacific North West winter, so
> the plywood had expanded so it was wedged between the forward
> bulkhead (between the locker and the cabin) and the aft
> bulkhead (between the locker and the lazerette. It took a few
> very careful whacks with hammer to get it out.
> 
> Once bulkhead was out, it was pretty easy to remove the tank
> itself. It would have been even easier if it was completely
> empty.
> 
> I bought a custom new one made in aluminum from Strait Metals
> here in Victoria: $700, but much better made then the previous
> one. I'll let you know in 20 years how it lasts. The standard
> plastic tanks available either were too small (loss of range) or
> too big or the wrong shape (wouldn't fit). No one I contacted was
> prepared to fabricate a custom tank out of plastic once they
> found out I was going to put gasoline into it.
> 
> The ABYC recomendation is that the fuel is not allowed to sit in
> the fill hose. My tank lies at angle with the lower end at the
> front, which is also the where the fill is. Therefore the tank
> has a custom fill spout welded to the top of the tank. At rest in
> the boat, the fuel never comes out of the spout. The spout only
> just barely fit back in. I had to cut a way a section half an
> inch high by 4 inches long in the fibreglass tabbing at the
> top of opening
> 
> The previous tank was held down with copper strapping (the kind
> used in plumbing, the stuff with lots of holes) in contact with
> the aluminum tank, which was a mistake. The front bottom rested
> on a horizontal bar with a lip to retain water, also a mistake.
> I'm pretty sure this bar is fairly standard. It runs side-to-side
> behind the engine and is made out of aluminium. The back end just
> rested directly on the (often damp) fibreglass of the hull.
> 
> The new tank is installed on plastic pads, bonded to the tank
> with 3M5200, as per the ABYC guidelines. The plastic pads are a
> cut up children's tool table I bought a garage sale because lots
> of pieces that looked like the right shape. It's made of
> polyethylene. 3M5200 does not stick very well to
> polyethylene (nothing does), but that's OK, because it's just
> there to keep moisture out from between the pad and the tank.
> The pads at the back raise it off the fibreglass. The pads at the
> front keep it out of the lip. I replaced the copper strap over
> the front of the tank with with stainless steel, isolated from the
> tank with another set of 3M5200 and polyethylene pads on the
> corners. This strap is bolted to the exising aluminum cross bar.
> The strap is tightened at the top of the tank with a long bolt.
> The tank is very stable. No amount of my shoving could move it
> and it doesn't shift even at extreme angles of heel. If the boat
> was inverted, there might be a problem.
> 
> Then I reinstalled the vent, the fuel line, and fill hose.  Where
> brass meets aluminum, I was careful to use yellow teflon tape.
> 
> Finally, I bolted the bulkhead back into place. Again it took a
> few whacks to wedge it into place with between the other
> bulkheads. Where I could, (i.e. where I could reach the far side)
> I through bolted. Everywhere else, I used self tapping screws.
> 
> Stephen
> #495 Quasar
> 
> 



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