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View Full Version : How much Gas to Carry?



3rdDonzi
06-20-2009, 08:22 AM
My '95 18 Classic (350 Mag Alpha) has 40 gals. fuel capacity but turns into a different boat with more than 20 gals. on board. Wants to porpoise a lot and has very small in trim window (No Tabs). I either have to cruise at 40+ mph or plow to prevent porpoising. Not an engineer but I would have thought that extra weight would dampen porpoising.
Obviously the fix is to not haul more than 20 gals. but I was wondering the opinions with all of the experience here. Different prop? Ballast?
Thanks
3rd Donzi

MOP
06-20-2009, 08:36 AM
Options are slim unless you want to take the boat apart and move the tank aft, the tank placement in out boats is to far forward. My 22 used to porpois like crazy always had to have some tab on at cruise speeds, when I did the stringers and transom I put another 40 gal tank just ahead of the engine. Everything changed handling and the porpoising disappeared, the original tank was fine so it stayed in the boat. On a few occasions I have filled it for longer trips or an event, the porpoising returns with a vengeance. Being a SB 22 it only burns little gas, on the 40 gal tank I have a range of over 100 miles with a little hammer down here and there. In your case I would run with 20 gallons rather the add weight, most try to dump weight rater then add!

Phil

gcarter
06-20-2009, 08:42 AM
Look for a different prop. A lot of it originates there.

BigGrizzly
06-20-2009, 09:19 AM
With no tabs it takes constant trim changes. Trim in to stop porpoising then slowly trim back out. You have to drive it, don't let it drive you. Not the prop is an issue but no prop will eliminate it. This is the nature of the beast.

Planetwarmer
06-20-2009, 10:26 AM
Not the prop is an issue but no prop will eliminate it. This is the nature of the beast.

Wouldn't the boat be rather slow with no prop? :kingme:

BigGrizzly
06-20-2009, 10:37 AM
Planet, yes but it will not porpoise either:kingme::kingme::kingme:

MOP
06-20-2009, 12:41 PM
Hee Hee a Gotcha!!!