Lower ends and gear ratios

[blueoval78]

I acquired a 1988 Bayliner Capri 1500 with a Force 50 motor in the spring of this year. The previous owner indicated she could pull a water skier no problem and could do 35-40 mph with the boat. She smoked a rock last fall and replaced the whole lower unit with one purchased from a used boat parts guy and did not run the boat after doing so. Now I have the boat and can only do 28 mph at best, even after rebuilding the carb and fuel pump. It also doesn't feel like I will be able to plane with a skier behind. If I bring the GF along I slow down to 22 mph. My question is, is the lower end interchangeable with other models that might have different gear ratios? Maybe she obtained the wrong model and the gear ratio is too low? I am @ 4500 rpm @ WOT by myself with a 13.5 pitch prop. I tried a 11.5 pitch prop which slowed me down to 22 mph and brought rpms up to 5000.

Any ideas?

 

[roscoe]

Re: Lower ends and gear ratios

I think the seller fibbed to you.
You are gonna need the 11.5 or a 10 pitch prop to pull a small skier.
Need to get the rpm up to 5000, or more.

You shouldn't be losing 6 mph if you are increasing your rpm by 500.

If you are gonna make it work, you, the girlfriend, and the skier, better weigh less than 120# each.

 

[blueoval78]

Re: Lower ends and gear ratios

Sorry, I meant 25 mph with 11.5 prop.

 

[metor99]

Re: Lower ends and gear ratios

You must of had the same sell i did. OOOO yes everything works perfect WINK, WINK. 175.00 dollars later now everything works.

 

[emoney]

Re: Lower ends and gear ratios

Why is it everybody wants to 'overstate' their boat's speed? A lot of these
folks get confused with speed and RPM. I actually have a friend that picked up a 20 foot center console with a 115 "rude on the back and SWORE it was
doing 51mph. Thought to myself, 'wow, that's really fast for that combo'. Once I got on his boat, first thing he did was open her up and then point to his tach and said, "See, I told you. 51mph". Of course, the tachometer read 5100 rpm.

 

[Frank Acampora]

Re: Lower ends and gear ratios

About 27 MPH with you alone and with a 13 pitch prop. About 22 MPH pulling a skier on two skis. Not enough power to pull a slalom skier--even with an 11 pitch prop. That's why I upgraded from a 55 to an 85 when my son started skiing.

Ask any seller how fast the boat goes and the magic number 40 is always mentioned.