Fuel Tank Capacity

rickuk3 · 15 April 2007, 21:23

I will be fitting a new under deck fuel tank or tanks to the Sea Harrier and I am trying to decide on the total capacity I should go for. Sugestions appreciated on what you feel the max & min capacity for a 6.4M rib with something like a 150hp opti on the back should be?
Richard

Searider · 15 April 2007, 21:46

I have a 160 litre tank in my Scorpion.

Generally big enough but could have done with a bit more capacity when going the the Scillies from Falmouth.

60 miles each way with a 30 mile blast on the middle day would have only left me with about 10 litres on return to Falmouth - so had to buy some there.

On the other hand I like to keep the tank full ish to reduce the potential for condensation and it does seem a waste to carry all that weight around!

How far you need to go between fill-ups will determine how much you need to carry.

Regards

Hightower · 15 April 2007, 21:46

Depends on the range you want to cover. If you're going to potter around the Solent all your life then 100 litres would be fine, for a Channel crossing I would be happier with 200 litres. I would guess that 150 would be a good compromise.

I'm having a 200 litre one fitted to the Vipermax. Someone did say (Pete 7 I think) that I would be running heavy all the time though, as you'll keep topping it up everytime you plonk her in the water.

I guess he could be right!

rickuk3 · 15 April 2007, 22:06

My initial thoughts were to fit 2 independant tanks of between 100-125 ltr each. For pottering around just fill 1 but for long distance trips fill both, is this a good or bad idea?
Richard

Nos4r2 · 15 April 2007, 22:10

Personally I wouldn't unless I could make them removable to flush and drain them. (condensation problems etc from empty tanks.)

Hightower · 15 April 2007, 22:11

Quote:

Originally Posted by rickuk3

My initial thoughts were to fit 2 independant tanks of between 100-125 ltr each. For pottering around just fill 1 but for long distance trips fill both, is this a good or bad idea?
Richard

I recon that would be a bad one as a fitted tank option as one of the tanks might well be empty for a longish period of time and might well present moisture/water problems.

If you did want to persue a two tank option then a main built in tank with a portable tank might be the answer.

Tim M · 15 April 2007, 22:12

Surly as long as you have some decent filters and water seperators condensation shouldn't be too much of a problem?

Hightower · 15 April 2007, 22:15

One advantage of two built in tanks is that if you had one fitted forward and the other midships then you could alter ballast for predicted conditions and load carrying.

Nos4r2 · 15 April 2007, 22:21

Quote:

Originally Posted by Tim M

Surly as long as you have some decent filters and water seperators condensation shouldn't be too much of a problem?

That's a very good point. I'm just paranoid about sucking the crap that sits in the bottom of tanks into the carbs. God knows where some of it comes from.

Hightower · 15 April 2007, 22:29

When I cleaned my Tank out in Kohaku I found no "crap" at all, probably the only time it had ever been inspected since installation.

rickuk3 · 15 April 2007, 22:33

Quote:

Originally Posted by Nos4r2

That's a very good point. I'm just paranoid about sucking the crap that sits in the bottom of tanks into the carbs. God knows where some of it comes from.

Most of it comes from the petrol stations

I have an old 1947 car and it takes its fuel from the very bottom of the tank and I was having problems with crap in the tank, I drained and flushed the tank and bought a water filtering bag from an outdoor shop it is just the right shape to fit over the petrol pump nozzle you would be amased at the crap it collects and no problems now.
Richard

jwalker · 15 April 2007, 23:18

Quote:

Originally Posted by rickuk3

I will be fitting a new under deck fuel tank or tanks to the Sea Harrier and I am trying to decide on the total capacity I should go for. Sugestions appreciated on what you feel the max & min capacity for a 6.4M rib with something like a 150hp opti on the back should be?

You're going to need 50galls at the very least for distance work cos you'll definately feel better knowing you've got some reserve...and you may well need it. Two tanks are good. If they're under deck tanks they will likely be V bottomed so make sure the fuel pickup is right at the bottom and at the rear of the tank and the small amount of crap you get with each filling will not be able to build up to cause a problem. If you can arrange it, being able to shift fuel fore or aft can be useful. Also, should you be unfortunate enough to get a tank or fuel supply problem, you'll be pleased to have a second separate system.

martini · 16 April 2007, 16:52

One of the bigger factors to consider is how much space you have under deck as the tank has to fit between the stringers. If you have a shallow vee hull and stringers are close together this may limit the size of your tank so two tanks may be the way to go.

Also carefully consider weight, not just the amount but position as well. Petrol weighs 0.737 kg/litre so 200 litres adds up to nearly 150kgs, thats an extra 2 pax!

Your hull manufacturer would be the best person to seek advice from, he should know exactly how much to squeeze in and where.

rickuk3 · 17 April 2007, 21:06

Thanks for all the replys, they have given me food for thought.
Richard