Fuel tanks

My little 31-foot trawler with her single Lehman carries 300 gallons of fuel in two 150-gallon steel tanks.* The tanks are getting tired and need replacement.** I am considering putting in two smaller tanks--75 gallons each, or half the current capacity--where the old steel tanks are now.* As I cannot contemplate travelling more than 200 miles or so between stops, I can't imagine needing a thousand miles' worth of fuel aboard.* I wonder what anyone else thinks.

Excellent idea, it's your little boat and you can do what you want!

However, I would leave room for the other two 75 gallons tanks to be installed later if need be. The problem I see daily is most of the vessels carry way to much fuel for the type of use they see.

El Sea/LC

"Suckin Sludge & Havin a Gas"

Our boat was re-tanked by the previous owner and the boat went from having a 450 gallon capacity in three 150 gallon tanks to 400 gallons in four 85 gallon saddle tanks and one 60 gallon day tank. The reduction in fuel capacity has not been an issue at all. In fact the smaller your fuel capacity the faster you'll go through the fuel and the fresher the fuel you have on board will be. You just don't want to reduce the capacity to the point where you can't make the runs you want to make without having to refuel at inopportune times.

The way we manage our fuel an opposing pair of the four 85 gallon "cube" tanks is usually empty at any given time. We can make a lot of two to four day cruises on the 230 gallons in the other three tanks. When the pair of saddle tanks we're feeding the day tank with get down to 20 or so gallons in each one we fill the two empty saddle tanks, finish emptying the two we've been drawing from and then leave them empty until the second pair is nearing empty.

The only time we ever fill everything is if we're going to be taking a longer, multi-week cruise.

Given the low fuel burn of the Lehman I suspect a total capacity of 150 gallons will work pretty well for you unless you are planning cruises to more remote areas where fuel stops are few and far between and fuel prices are high. The suggestion to leave the unused space clear for additional tankage that you or the next owner might want someday is a good one, I think.

A couple of things:

At 31ft and 300 gallons with a FL120 you have a hell of a lot more range then a 1K miles.

We removed one of our tanks on our 36 which left 175 gallons and our single 120. We often cruise for weeks including 22 hrs offshore a few weeks ago and fuel capacity is only ever an issue when we want to stock up on the better priced stuff. What their saying is spot on, you want to match your capacity to your use. You don't want partially filled tanks which encourages algae growth, you don't want old fuel and you don't want to be carrying the weight of access fuel.

200 miles between stops is more likely then you might think.

I would install about the same as stock capacity,in 4 tanks , leave 2 empty forever , or bring rum back from the Carib.

The next owner may decide longer coastal trips are fun, and fuel is cheaper in different states.

I would then install a gravity to the engine day tank of METAL that would hold 24+ hours of running.

It would be metal so it could be a self servicable tank.

That includes a well in the bottom with drain as a minimum ,
or far better a setup I have described on many occasions,shown in Skeen's Elements of Yacht Design as a Sparkman + Stephens tank..

Thanks for all the feedback. I think I will go with "Plan A." Bioth FF and Marin mention four tanks and a day tank, which seems a wonderful way to go; I may put that into my planning, but it is beyond the scope of my budget. My thoughts were exactly those of El Sea and Daddyo: I don't want to be carrying around too much fuel, letting it get old and slosh around; but the final point is that the space where the original tanks lay will remain unusued in case a future owner wants to add tankage another time.* Thanks again for the prompt and helpful responses!

-- Edited by Chris491 on Sunday 29th of August 2010 10:31:08 AM

I carry 380 gal and if the time comes I will reduce fuel capacity to something more like 150 gallons. I'll use the saved space for storage and extra water capacity.

*

Wow... Good ideas! I'll do this when the time comes to replace my steel tanks.

Any pics of y'alls installs?

Pics would be great to see. I also want to get the low down on a "day tank". Fast Fred, I can see where that could give you a second chance at providing good fuel to your engines. How would it work? Electric pump to push the fuel from the tanks up to a tank mounted higher than your engines? Where would the Racors be? Before or after the day tank? Is it enclosed? What do you do with the remaining fuel? Sorry to get off the subject so much!

The Day tank is usually installed so it can be filled with a pump from a fuel manifold .
You select the tank the fuel is to come from and operate (hand or electric ) the fill pump.

Many are set so the tank is hand pumped and the overflow goes back to #1 tank , not much does as its noticible with the hand pump when its full.

The fuel is filtered by the dual Raycors before getting into the day tank, tho some will have an additional top fill, so injector / fuel pump preservative can be installed for lay up , or the tank topped in an emergency.

The day tank MUST have a bottom drain so it can be cleaned , and will feed the engine and get the return fuel.

El Sea,When I had new tanks made for my boat I asked for 2 35 gal tanks to replace the 50 gal original tanks. When I came down from Alaska they already had 50 gal tanks in. I let it go.
Good for you though and make them do it as you dictate!