Fuel tanks, under deck or above...

chewy · 23 September 2011, 19:02

Still looking at what to do with the tanks on my 21. I have two stainless tanks that are made for the RIB but my only concern is that if I have problems in the future then the deck will have to come up.
The fillers will come up next to the console, I can fit an inspection hatch above the tank fittings and another at the stern to get access to the lines and through deck fittings.
Usually the deck on the Atlantic is screwed down but I'm going to screw it down and glass over it so its watertight and it seems a shame to run the fuel lines through it.
The only other solution apart from a big tank on the deck is a couple of Mr Tilley's flexible "race" tanks strapped on the tubes.

Discuss.....

HUMBER P4VWL · 23 September 2011, 19:23

Above. Easier to check level, easier to change, easier to fill, just easier. Unless you want pure distance. Then go under deck and over.

chewy · 23 September 2011, 19:36

Cheers fella, next question is where to put them if I don't use flexible ones?

Turbodiesel · 23 September 2011, 19:59

Under the deck with some good fuel filters!

chewy · 23 September 2011, 20:34

So apart from a hatch over each tank for access to fittings and on at the stern would would recommend anything else?
There is two fixing points at either end, I also want to bed them into something, is sikaflex ok for this and if so which one?

Poly · 26 September 2011, 14:31

Chewy, I would go under. If at somepoint they develop a fault in the future and you can't fix it without major expense / time&effort then you can always revert to "on top" tanks. Once you've glassed that deck in you can't really decide they would be better down their afterall...

Nasher · 26 September 2011, 16:31

Chewy

Under gets my vote, the weight is then low down where it works best, and you save deck space.

For some reason I noticed that a lot of RIBs at the Southampton show this year had large removable panels in the deck to get to the tanks.
I’ve not noticed this before, which is either me being blind or the manufacturers are now taking a different approach.

All of them were screwed down, and in some cases Consoles, seats etc were screwed down over the top of the join, so would also need to be removed to get underneath.
Obviously unscrewing stuff and a bit of faffing around is preferable to cutting and re-glassing.

If I can ever afford a new boat it’s something I’d build in from the start.
If you are doing major surgery anyway, why not build some extra strength in around the hole and have a removable panel.

Nasher.

GordyP · 26 September 2011, 18:58

Can you not have a similar set up to the Arctic where the top of the under deck tank is flush with the deck? I can send you some photos of mine of you like.

jyasaki · 27 September 2011, 15:26

Quote:

Originally Posted by Nasher

For some reason I noticed that a lot of RIBs at the Southampton show this year had large removable panels in the deck to get to the tanks. [snip] All of them were screwed down, and in some cases Consoles, seats etc were screwed down over the top of the join, so would also need to be removed to get underneath.

That's how mine is set up, though it's an aluminum hull. There's a roughly 2.5' x 7' plate screwed down, then the console is mounted over the rear part of that. Though it allows access to the tank (theoretically, anyway), it would be a major PITA to actually get to it. As you say, still better than having to cut access to it though.

jky

wavelength · 29 September 2011, 21:01

for me-above in the consol. We have a 90litre in there fits fine. Can dip it to see what is actually in there, the volume is stacked vertically in a column, if ya see what I mean, so there is less surface area. Which helps as the level gets low. The CofG may be higher but it doesn't move as the boat changes trim angle, or move violently to the back as it can with a shallow underfloor tank when the boat is launched over the side of our particularly unpleasant slipway. On long trips we have two extra 30litre portable tanks that are handy for balancing the boat and to take to the filling station when we get to a non petrol marina.

BogMonster · 30 September 2011, 01:05

Under deck - so much nicer having the 150L tank in the Osprey that I can do half a dozen trips with, than the silly little console tank in the Humber which I had to fill up every time just to have a reasonable range if I did want to go far. And you get extra storage under the console if there is no tank there.

Jus · 30 September 2011, 06:24

If they are well made and fitted I would say problems with the tanks are unlikely. It is worth adding fuel conditioner to any fuel left stored for any length of time and decent fuel filters as others have said.
Also, as fuel prices only ever seem to go up, I find it is worth being able to store as much as you can!

Pikey Dave · 30 September 2011, 09:22

I've never had a boat with above deck tanks. It's never occurred to me to have portable tanks in anything but a v/small RIB or squidgy. As already mentioned, fit good filters (Racor with the clear bowls

) Good housekeeping, fuel conditioner for winter storage (I use it year round) & you shouldn't have any problems, plus you gain valuable deck space/storage.

chewy · 09 October 2011, 14:26

Cheers for the answers, haven't got any further yet, hopefully getting a workshop to store/work on it so should make some progress over winter....

wavelength · 09 October 2011, 15:00

Quote:

to always be a problem with the underdeck tanks as they usually let water in and petrol out. On mine the problem was due to two things. Firstly the fuel sender units are made of different metal to the tanks and so corrode and leak. Secondly the fuel pick up in the tanks is not at the bottom so even if you run the tanks "dry" there is still about 20 litres of fuel / water left in the tank which can only be removed through the sender fixing.

ok its a specific boat...but it ain't always good under the boardwalk and if it goes wrong its a pain.
On a long run, with under deck or in the consol tanks, I would by preference also carry the portable tanks, and run on them first. Its so much easier when you get to a harbour/marina without a petrol pump. And up in God's own country that means all of them. Otherwise you are carrying jerry cans and I may as well run with sommat I can simply plug into the system and turn the changeover valve to them rather than try and pour fuel in whatever the conditions might be at the time.