SunCat's Yamaha 4hp fuel consumption

[Mike Howell]

My new to me Yamaha 4HP 4 Stroke is a 2001. It's pushing my Sun Cat. Does anyone know the fuel consumption of the OB?

I've always used the rule of thumb 'Divide the HP by 10' and that's the number of gallons per hour fuel consumption at full throttle. So my 4hp would be 4/10 a gallon at full throttle in an hour. Although I've alway heard of this Rule of Thumb, but I've never tested it.

I'm getting ready for the B.E.E.R. Cruise and would rather take my 3 gallon tank instead of my 6 gallon tank (my 6 gallon tank will fit). If the rule of thumb is correct, I should be able to get 6-7 hours at full throttle, but the SunCat doen't need full thottle, so I'm GUESSING 8-9 hours at 1/2 throttle. Maybe 40 miles on a 3 gallon tank of gas?

The B.E.E.R. Cruise will be a good time to document my fuel consumption since there will be a minimum 30 miles of motoring.
.
Anyone have 'real numbers'?

Thanks,
Mike Howell
St Marys Ga
SunCat

[Shawn]

Mike,

I think the 6hp Tohatsu sailpro is rated for 1/2 gallon an hour at Wide Open Throttle. Around 3/10 or 4/10s a gallon an hour at WOT is probably in the ballpark for the Yamaha. But you won't be cruising at WOT. So your actual consumption should be considerably lower. On the sailpro I guestimate that I am doing may 1/4 a gallon an hour when I'm cruising at around 4-5 knots.

Shawn

[capt_nemo]

Mike,

I have one of the newer breed of YAMAHA 4HP 4-strokes, which is only a few years old, on my Sun Cat.  IT SIPS FUEL.

It moves the boat at hull speed (5.2 knots or 6.0 mph) using ½ throttle, or slightly above, depending on wind, wave, and current. Keep track of your speed on GPS and don't use any more throttle than necessary. No reason to WASTE fuel trying to exceed hull speed.

My research found a test years ago where a 4 HP YAMAHA on some small boat achieved 60 MILES PER GALLON!

Not saying ours would do so well, but for longer trips I draw from a FULL 3 Gallon Tank and have a small 1 gallon Tank as RESERVE.

Keep us advised of your fuel consumption at B.E.E.R.

Hope this helps a little.

capt_nemo

[Catawampus]

I have a 2002 Yamaha 4-stroke 4 hp. Gotta agree, she sips fuel. Had a 6 gallon tank, but had to remove the cockpit grate to pull the tank out of the locker, so I changed to a 3 gallon with some concern.  No need for concern, 3-day weekend with liberal use of the engine during lulls, I thought I better top off at the sail club before heading home. My judgement was just as good as ever, sadly. Squeezed 4 tenths of a gallon into the tank.

[Catawampus]

Also, she pushes My Suncat at 4.7 knots at about 1/3 throttle. Above that I can push her to 5.2 knots, but it's very noisy. I suspect that there's considerable cavitation above 4.7 knots.