Adding under deck tank.

TheWoodCrafter

Chief Petty Officer
Joined
Nov 20, 2007
Messages
414
New here and will have many questions.
I am restoring a 1966 Powercat 15ft, 4 seater, outboard.
I bought a Merc 1100SS for it and the portable tanks will be too small.
I bought a 25gal tank for under the deck. Never installed one before.
I will be adding an electric pump, I have a deck fill/vent coming with the tank.
Any special pump needed?
How well should I support the tank?
Any insight would be a big help.

Roger
 

SpinnerBait_Nut

Honorary Moderator Emeritus
Joined
Aug 25, 2002
Messages
17,651
Re: Adding under deck tank.

Welcome to iboats.
Let's get this to the boat restoration and building forum.
 

reelfishin

Captain
Joined
Mar 19, 2007
Messages
3,043
Re: Adding under deck tank.

I've had several boats with in hull tanks, none of them had any special fuel pumps, you pumped up the ball and the engine pump did the job just fine.
Depending on how its mounted and vented, I would consider an under the floor/in hull ventilation fan and some ducts to evacuate fumes.
 

wire2

Lieutenant Commander
Joined
Jun 25, 2007
Messages
1,584
Re: Adding under deck tank.

What material is the tank made of?
Most likely plastic or aluminum, possibly stainless. Keep in mind, when full, 25 gal of gas weighs ~ 200lbs, so support the bottom of the tank accordingly.

I agree, you shouldn't need an electric fuel pump, the outboard should easily be able to lift fuel the extra 10-12" from under the floor.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,035
Re: Adding under deck tank.

Roger, First of all that Merc 1100 will likely overpower that boat. Check your ordanances.

secondly, Boats of that size do not usually have built in tanks, since the height f the floor is insufficient to acomodate them. How about a pair of 12 gal above deck tanks? It will be easier to balance the load and refuel.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Re: Adding under deck tank.

secondly, Boats of that size do not usually have built in tanks, since the height f the floor is insufficient to acomodate them.

Ayuh,.......

That was My 1st thought...............

Have you Looked to see exactly how much room you have to work with,..??..??....
 

TheWoodCrafter

Chief Petty Officer
Joined
Nov 20, 2007
Messages
414
Re: Adding under deck tank.

I have not purchased a pump yet, I assumed I would need one.
I can try without one.
Under the deck is small. At your feet under the dash is a short bulkhead. Beyond that it drops down a little then pitches up to the bow. The tank I ordered should fit nicely, made of plastic. No brackets on the tank for mounting. Can I support the tank with foam?
I didn't think I would need any ventilation. The area is open 12" tall by the width of the hull, although it does step down a little.
As for the engine size - I hope with the right trim and ballast it should be fine. The PowerCat sight has several examples of this setup. They say it will run about 65mph. I would like to be able the propel 4 people UP the Colorado River at a decent speed. With my Evirude 90HP it was a crawl and went through 1 6gal tank before we got where we wanted to go.
So with a 25gal tank I hope to spend the day before refueling.

Thanks for the input.
Roger
 
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