The Pascoe Method- Stabilizing Fuel Tank

[Capt. Bob]

Well I like the mounts on top of the tank. Personally, since the coffin is thin walled, I would epoxy wood blocks to the sides of the coffin at the mounting points and attach to the blocks. Same method used to mount a seacock (raw water intake) to the hull.

Something like this.


That should give you plenty of stability in each direction. No need to screw into the stringers. Do your layout with the old tank so you can get the mounts attached to allow clearance between the thickness of the wood and the mount itself. If your level of confidence is high, mount the blocks while the tank is being built. If not, just wait till its done.

Good luck.

[RickK]

If your stringers are solid and secure, I wouldn't fret about tieing to them.  You could always lam a couple layers of cloth on the areas that you will tie into.

[boatnamesue]

I also like the idea of mounting blocks.  The coffin gradually widens, so i'll have to wait until the new tank is ready to make the blocks so the angles are snug.  Unless you know of another method.  Even though the fabricator will have my old tank to replicate, I'd hate to epoxy in the angled blocks then find out the angles are off.

[Capt. Bob]

After thinking about it some more, I would agree with you. Once you have the new tank, you can dry fit to get it just right. This also allows you some "wiggle room" fore to aft.

Sounds like a plan.

[boatnamesue]

You know, if it wasn't for my good conscience I'd be 100% with using the complete pascoe method.  It's simple and the least amount of tank prep time.  I'll have this boat for maybe 5 more years, 7 at most.  I'll sell it off and buy a 19-6 or 22-2.  My point is, I won't be the owner of this boat when it needs another fuel tank.  Bonding the pvc strips to the coffin bed with 5200...extracting the tank will be an absolute nightmare.  It would have to be lifted straight up to break the bond, and along with it would come the coffin or pieces of it.  It won't be my problem....but then my conscience kicks in ;)

[Brendanpd28]

An aluminum tank installed properly should last many years. Allowing the tank to dry out is priority number one as you already know. #2 IMO is to avoid dissimilar metals completely. Especially brass since aluminum and brass are so far apart on the galvanic scale. Even stainless fittings can cause corrosion as well. Stick with aluminum everything and use a good thread sealant. Not tape. All this being said, I would have went poly myself if I could of found one that would work. Most would either need to get a custom made poly tank or sacrifice valuable capacity to find one that fits in a stock 170 coffin. I must say I do appreciate the fact you are thinking about the future owner though. Good luck with your install and I look forward to seeing your method of securing her down.

[wingtime]

I didn't trust the idea of only glue holding down my tank that's why I went with the straps.

[Brendanpd28]

I haven't secured the coffin lid back down yet and I've been playing with the idea of milling up some tapered PVC blocks to pressure fit on either side of the tank as a little extra security. 5200 them in place.  Maybe I will for a little extra piece of mind Now lol.

[mshugg]

For me, the key is nothing to hold or trap water next to the tank.  I used the 5200/strips on the bottom and chocks on the top.  Any water that makes it into my tank compartment has a free pathway to exit.  If you use straps they may block the flow of water out of the compartment.

[boatnamesue]

I dropped the tank i'm replacing back into the fuel coffin to gauge the amount of space. I'm definitely bonding pvc strips to bottom to elevate tank.  But I'm still undecided as to how i'll anchor the tank on the sides...foam, glassed blocks/precision board as a wedge, glass in 4 mounting blocks above level of tank secured to welded tank tabs using screws. As you can see from the pictures, space is limited. 2" at top and bottom, 1/2" on sides.

I've ruled out anchoring to the stringers.  Instead the 4 glassed in mounting blocks would be the primary anchor.  I figure getting at least 1.5" of screw purchase into the glassed block, 8 screws–4 blocks, is more than plenty of stability.

[wingtime]

2" wide straps made out of aluminum screwed to the sides of the coffin are MORE than strong enough.  The factory did it that way and they have been holding the tanks in place for years with no issues.  It's easy to get carried away trying to make the perfect install.  Starboard strips glued to the bottom of the tank to elevate it and hold down straps will last 25+ years.  Don't overthink this.  Just install it and get on with enjoying the boat.

[boatnamesue]

2" wide straps made out of aluminum screwed to the sides of the coffin are MORE than strong enough.  The factory did it that way and they have been holding the tanks in place for years with no issues.  It's easy to get carried away trying to make the perfect install.  Starboard strips glued to the bottom of the tank to elevate it and hold down straps will last 25+ years.  Don't overthink this.  Just install it and get on with enjoying the boat.

If you can direct me to a picture of this setup please do.  I assume the screws are lagged into the stringers since you didn't mention mounting blocks?

[boatnamesue]

Disregard my last.  Found this:

[McAllgeyver]

I went with the 100% Pascoe method. Have not put the 19-6 in the water yet but I really don't think there will be an issue. The tank has 5 glass strips (1.5"x18") 5200 to the bottom of the tank and then the tank was placed on top of 5 small ribs you see with 5200. My tank was lightly sprayed with green zinc chromate for some extra protection.
   

[wingtime]

Here ya go





Odds are the screws holding the straps to the sides of the coffin box are also penitrating into the stringers. The screws are in sheer so they will hold very well anyways.