how do they go

[ewenm]

hi

can anyone give first hand experience as to how 4 cylinder mercruiser/VP,s go in 18 foot bowriders??

like for instance the Mariah 18sx or the sea ray 185 sport

maybe max 4 adults on generally protected bay waters

seems to me a compromise with to little power with the 4 cyl and to much weight with the V6

obviously i would water test any boat to determine for myself what i like best , but i am seeing if

i can narrow my search down a little

i guess what i want is something easy to tow behing a jeep cherokee be easy to handle on my own, and still jump up and run

i guess around 45- 50 mph at wot, and with a cruise around 25 - 30 mph

if the 4 cyl could satisfy i would be happy with that

i just need some real world feedback

ive checked out both above quoted boats on youtube and they all seem to run ok but then thats not real world is it.

any feedback much appreciated

 

[Mischief Managed]

Re: how do they go

Not a bad power choice for a lightly loaded 18 footer, won't get anywhere near 50 MPH though. A 4.3 would be more fun and a lot quicker/faster.

 

[Chris1956]

Re: how do they go

I had a SR 18 foot Bowrider with a V6. It would get 42MPH max, downhill with the wind. A friend of mine had a similar sized boat with the 3.0l 4 banger. Th 3.0L motor has more vibration than the V6, and lots less power. That boat would probably do 35MPH.

All in all I think the V6 is a better power package for that size boat.

 

[gtochris]

Re: how do they go

I've had both, currently have the 3.0L in a 19ft Stingray.

It works good for our needs, only issue is slalom skiing.. but perfect for wakeboarding and up to 6 passengers.

 

[ezmobee]

Re: how do they go

My uncle has had a 3.0 in a Sea Ray 175 since be bought it new in '95. He has used it HARD for primarily watersports and it's been fine. In fact, he just picked a real cherry '98 Sea Ray 185 that he got a nice deal on, and it also has the 3.0. I'll tell you, those things use like NO gas. It's quite amazing. I wouldn't want it in much of a larger boat but in that size it's just fine.

 

[swift1]

Re: how do they go

I have an 18 ft Chaparral b/w with the 3.0. With just myself on a calm day I can hit low 40s at WOT. But with my normal load (2 adults, 2 kids) mid to high 30s is the best she'll do. . Most times thats fine with me but there are some occasions when the 4.3 would be welcome. If there are more adults on board she does struggle to get on plane that's for sure. No problems pulling a tube and a comfortable cruising speed is about 25-30. Towing is a breeze with my 6 cyl Trailblazer.

 

[steelespike]

Re: how do they go

I don't have first hand experience with a 3.0 or 4.3 but I have delt with the various boats with these motors on the prop forum.
While there is the occasional; 3.0 that can manage about 43 or so most hover around 40 and require careful prop selection for
water sports with anything over a couple of people.Typical 3.0 hp is around 135 or 140 hp.
The 4.3 usually hovers around 50 some a little more and others around 48-49. 4.3 max hp is around 220 obviously a lot more
performance. By the way a 140 will use about 14 gallons per hour at wot. a 220 would use about 22 gph at wot.
By the way a boat running at 50 can get in trouble on the water quicker than one running at 40.
Of course you need to use caution at any speed.

 

[ezmobee]

Re: how do they go

By the way a 140 will use about 14 gallons per hour at wot. a 220 would use about 22 gph at wot.

Isn't that more of an outboard formula?

 

[steelespike]

Re: how do they go

Isn't that more of an outboard formula?

Its based on hp. It takes a certain amount of fuel to produce a certain amount of power.
actual percentage of rated hp will vary from slightly above 10% to slightly less than 10%.
Percentage remains roughly same whether pushing a house boat or a runabout.

 

[mphy98]

Re: how do they go

I had an 18 foot Thundercraft with a 4cyl IO. It was a tri hull and The most I could get with just my son and myself was 43mph by gps. With fishing gear and 4 people dropped to 32 max speed. It was reliable and a good boat until the Starcraft came along .

 

[ezmobee]

Re: how do they go

Its based on hp. It takes a certain amount of fuel to produce a certain amount of power.
actual percentage of rated hp will vary from slightly above 10% to slightly less than 10%.
Percentage remains roughly same whether pushing a house boat or a runabout.

Would not a 130 outboard use WAY more fuel than a 130 4 cylinder I/O? My experience would certainly indicate that it would.

 

[bnicov]

Re: how do they go

I'd be thinking more of a 4.3 in an 18+ ft boat. The 3.0 is kinda small and will be working really hard to get the boat up on plane with a few people on board.

 

[Chris1956]

Re: how do they go

The carb OB will use lots more fuel than the I/O, for roughly the same application, in my experience. Of course that is offset (at least mostly) by the cost of maintenance and repairs for the I/O (AF Paint, Bellows, U-Joints, Gimple bearings, manifolds, starters, ciculating pumps, hoses, belts, thermostats etc).

 

[steelespike]

Re: how do they go

Keep in mind the 10% is approximate rule of thumb for easy figuring
a 3.0 135 hp in a Larson weighing 2045lbs uses 10.8 gph @ wot 35.2 mph thats about 8%.
and 3.3 mpg.
A Evinrude Etec 130 hp on a 2380lb Carolina Skiff uses 10.7 gph @ 39.8 MPH about 8.2% and 3.7 mpg.
So about 10% is ok to figure in your head Again some may be more than 10% some less.

 

[UncleWillie]

Re: how do they go

Keep in mind the 10% is approximate rule of thumb for easy figuring
a 3.0 135 hp in a Larson weighing 2045lbs uses 10.8 gph @ wot 35.2 mph thats about 8%.
and 3.3 mpg.
A Evinrude Etec 130 hp on a 2380lb Carolina Skiff uses 10.7 gph @ 39.8 MPH about 8.2% and 3.7 mpg.
So about 10% is ok to figure in your head Again some may be more than 10% some less.

+1, It is just a rule of thumb, Not the law of thermodynamics, and it is a very fat thumb!

Given no specifics, estimate at 10%. You can hope for 8% but be prepaired for 12%.
and remember that 12% is 50% bigger than 8%. (Your mileage WILL vary!)
It is only a ballpark calculation, it is like saying that the ball landed somewhere beween the dugouts and the outfield fence.

 

[ewenm]

Re: how do they go

thanks for all the comments.

if i had a choice and was buying new it would be an MPI V6 however i will be buying used, up to 4 years old, and by far the majoriety of bowriders for sale here in Australia in the 18+ foot range are 4 cylinder, when you get to 19+ its about 50/50

my personal experience is with the V6 and thats what i,ll be looking for

probably in our winter when prices are a little lower