How fast will it go?

[5speedhemi]

Hello, I am currious as to how fast you all think this boat might go! I have a 1978 Starcraft Mariner V5-22. I've never had it in the water but all your practical boating experiences should give me a ball park on performance. It has a 260HP 4BBL Ford 351 in it and the outdrive is a Stringer 800 with a large propeller that I believe is @ 19 pitch. The boat weighs @ 1550 to 1600 as best as I can tell from my research. The aluminum hull and the wide 96" beam and 22' long hull should get it on plane in no time! I'm gonna throw out a 50 mph... What do you think?

5 speed

 

[ezmobee]

Re: How fast will it go?

5-speed......I remember what boat you have but our other users might not. You may want to include that information. I'll throw out 40-45. That deep V of yours it going to provide a GREAT ride in the chop, however you will sacrifice speed.

 

[mikezohsix]

Re: How fast will it go?

you need your outdrive ratio to figure it out.

engine rpm at redline divided by the ratio gives the prop rpm.
prop rpm X pitch gives the theoretical forward motion in inches per minute.
turn that into miles per hour by multiplying by .000942
add in a slip factor, say 10% and you get your speed.

Hull shape affects slip.

4000 rpm/1.5 outdrive ratio = 2666 rpm x 19" pitch = 50666 inches/min x .000942 = 47.7 mph, 10% slip = 42.9 mph

not sure what your outdrive ratio is, or what the right slip factor would be.
the math seems to work out though.

 

[5speedhemi]

Re: How fast will it go?

Wow...that's one heck of an educated guess!

5speed

 

[Boss Hawg]

Re: How fast will it go?

Wow...that's one heck of an educated guess!

5speed

I have a headache just reading it
I spent a summer in McAllester a few years back- You sure have some beautifull lakes there
But you can keep them dang tornatos

 

[86 century]

Re: How fast will it go?

50 mph is when the wife starts to yell slow down. I say 50 mph

 

[5speedhemi]

Re: How fast will it go?

Well 50mph + is what I am wanting so if it don't do 50mph... it will when I get done with it!


5 speed

 

[86 century]

Re: How fast will it go?

My 20' century will run right at 50mph it has a 260hp merc alpha 1(no clue on gears) with a large 15p ss prop. This is at 4100rpm is where it starts to ventilate. The up side to it is it will do 50 full of fuel(40gal) and over loaded with people and junk.

 

[5speedhemi]

Re: How fast will it go?

Heck yeah! Thats because of the 15 pitch. I bet that sucker has a hole shot! I have a huge suspicion that my fuel tank is much larger than 40 gallons! Any clues howmuch guys?

5 speed

 

[5speedhemi]

Re: How fast will it go?

I called the old owner and he said 60+. He said that he would of added 2 deg more pitch to what he had on it if he kept it. The engine tached out at 5500 RPM fast he said...

5 speed