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Discussion Starter · #1 ·
Im making a new alum bow tank to replace the orig fiberglass tank. the orig was about 16 gallons, with only one baffle separating the front ~6 gallons from the rear ~10. My new tank is going to have a little bigger footprint and a little taller, ending up about 23 gallons. It is triangular (from top) with square sides.
My baffle plan was to basically divide it in thirds. I was going to run strips that leave a gap of 1/2 inch at the bottom and top. I figure this will keep major sloshing down but still allow for filling and venting.
How close should the pickup be to the bottom? Straight cut or angled? I was considering adding a small baffle around it, maybe 1 inch high, in hopes of keeping some fuel trapped around it like a sump. What diameter pickup for 550 hp or under? I am planning to make a bolt-on fitting that has the pickup, sender, and a (plugged) return in case i ever go to efi.
This is a 18' deep V lake boat, skiing, pleasure cruising... so i dont need a max effort race setup.
 

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when i build tanks i run the pickup all the way to the bottom - about 1/16th from touching and angle cut it that way nothing can get in between it and the tank and block it. I don't usually baffle the pickup as i like it to be fully unobstructed but I do route the tube into the area of the tank where i have designed the tank baffles to keep most of the fuel (the rear) Admitidly I have never built a tank for a boat but i have cars and I wouldn't see any reason to do it differen't in a boat. Same with an efi setup with in tank pump i build a mounting ring/flange and design the tank so the pump/filter sits on the bottom and build baffles to keep fuel to that area of the tank.

as far as pickup size i would suggest 1/2" its easier to bush it down then make it bigger later on.

hope that helps
 

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I had to cut my bow tank open earlier this year due to the baffle breaking loose and a rust hole (steel tank)

Anyway I found that the baffle went all the way from the top to the bottom, and it went front to back in the tank. It touched the back wall and went about 3/4 of the way to the front. On the back bottom corner it was 45ed so that fuel could flow between the sides at the bottom. And last year I was running all year with the baffle broken off and floating in the tank and I never had a fuel slosh problem.....I even ran it out of gas, and I never knew it was running out till that thing was bone dry.
 

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oldslomobile
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When I built mine it is verry simalar to what you are discribeing. I made two baffles in it with mulitple holes in each one at different hights (so they don't line up)they went from top to bottom with what I would call a mouse hole in the top and at the very bottom that was 2" dia. 3 of them in the bottom of rear baffle unsure on the front any more, a small sump with a small baffle flush with the bottom at the rear. It has a -6 line out in it now supplying 425hp and also a -10 incase I need more some day.
 

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If you are going through all that....why not shit can the bow tank all together and run saddle tanks. Who wants all that weight in the bow of an 18 foot boat. JMO ;)
 

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Discussion Starter · #7 ·
I thought about saddles since they make poly tanks that look like they would fit (at first glance anyway), but I didnt want to re-rig everything that wasnt there (fillers, plumbing for 2 tanks, vents, etc) for a closed engine bay setup. At this point I just want to get this thing on the water, if I end up re-doing it next year or two when I am looking for that next 3 mph, so be it. This is a low dollar, high freeboard, lake cruiser/tube puller/ski boat. Im not going to be lining up against any v-drives or blown pickle fork jets.

I have some shop friends helping and I should be able to get the bow tank done in another week with less than $200 in it, and minimal hassle.
 
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