am i too slow?

[ratking20]

i just bought a 1992 sea ray 220 bowrider
it has a 5.7 260 hp mercruiser i/0
engine was just tuned up
dry weight for boat is 3150 lbs
im maxing out at almost 40 mph
should i be a little faster
i know the engine is 18 years old but i was expecting closer to 50 mph ????

 

[cr2k]

Re: am i too slow?

Sounds a little on the slow side to me.

What is your WOT RPMs?
What size prop are you turning? How many blades?
How did you determine your speed?
Was the water flat, choppy or rough?

 

[ratking20]

Re: am i too slow?

i clocked it today. my speedometer isnt working so i used a program on my phone that uses gps to determine speed. it jumps around but u can get an idea. i clocked and compared in a moving car and it was pretty close. my tachometer says im wot at 3900. im supposed to be at around 4500. i saw my mechanic about this and with his light thing he told me my meter was off about 10% (his meter read 1100 when mine read almost 100) so with that i should be about right. water was pretty calm. i just changed props from a 15x17 to a 14x19 i believe. i went to the prop that the motor says it should be using as per sea ray and the mercruiser book

 

[ratking20]

Re: am i too slow?

anyone else???

 

[Bob_VT]

Re: am i too slow?

Have you weighed the boat? Are you sure you are not carrying along a few hundred pounds of water in your foam?

This might be a prop question so I will move it.

 

[ratking20]

Re: am i too slow?

i did not weigh the boat, how would i do that anyway? my question is... should my top speed be around 40 mph or should i be going faster with this boat/engine??????????

 

[arks]

Re: am i too slow?

Weigh the empty boat on a truck scale then deduct the trailer.

IMO your speed is about right considering the age of the engine. My old 23 Wellcraft Nova 'performance' boat would only do 44-45 MPH on a good day with a BRAND NEW Mercruiser 5.7 EFI and a labbed prop. They made boats a lot heavier back then. Yours is about 1000 pounds lighter, so maybe you should experiment with the prop- get it tuned or cupped.
I'll assume you've got the outdrive trimmed up a bit when running WOT...? If not then you're hull is bow-plowing and not efficient, causing speed to be scrubbed when on plane.

 

[ratking20]

Re: am i too slow?

i do trim it up a little, im just getting used to using the trim

 

[NHGuy]

Re: am i too slow?

I'd suggest getting the tachometer fixed. If it's wrong and you overspeed the engine it could be an expensive problem.
BTW I have a 5.7 carbureted Mercruiser on a smaller lighter (I think) boat. It will go to 4600 RPM which is the engine's limit before it hits wide open throttle. It has a 19" pitch prop. When I trim it up I have seen 48 MPH at 4500 RPM.
I can't go Wide Open til I get a taller prop, and the finance department says I need to wait.
40 MPH might be max if your Ray is as heavy as they appear.