1985 Marlin Bowrider 15' 6" OMC 400 stringer What is the rpm range?

[pipefitter-123]

I just traded a dirt bike for a well maintained 1985 15' 6" marlin bow rider Deep V, it's equipped with a I/o G.M omc 2.5 120 hp engine, and omc 400 stringer outdrive. A nice 15 X 17 Stainless prop. It came with an Aluminum 13 3/4 X 15 prop (what should I run for speed?) This is my first boat & learning as I go. I Just had a new water pump, upper & lower seal kits, & engine fluids changed. Unfortunately It's been raining so much I haven't been in the water yet.

I'm really curious how fast the boat should go (MPH)?
what range rpm to run to get best performance without ruining the engine?
Stainless or Aluminum prop
what is the gear ratio
Has anybody heard of this boat? What are Marlins pros n cons?

I greatly appreciate your help. Thanks, pipefitter-123

 

[Howard Sterndrive]

Re: 1985 Marlin Bowrider 15' 6" OMC 400 stringer What is the rpm range?

I'm really curious how fast the boat should go (MPH)?

I would guess max speed 37mph to 41mph depending on load

what range rpm to run to get best performance without ruining the engine?

select a Prop that limits your WOT rpm to 4200 rpm to 4600 rpm.

You can run it up to about 4700 without damage
Most folks cruise around 3200 rpm to 3600 rpm for economy and engine longevity.

what is the gear ratio

21 / 18 Upper

13 / 26 Lower

 

[chiefalen]

Re: 1985 Marlin Bowrider 15' 6" OMC 400 stringer What is the rpm range?

You can't run no way a 15 x anything prop. No bigger then a 14 x something prop. 15 will hit the top just won't fit. Plus 13 spline.

Agreed 4200-4600 rpm you run it at 4700 your gonna blow that motor up.

Speed don't mean nothing it's the rpm's and make sure your gauge is accurate.

My guess a 14 x 17 the larger the last number to stay within the 4200-4600 rpm range.