what prob to use?

greenleemm

Cadet
Joined
Nov 5, 2006
Messages
11
I have a 1981 seaswirl 16' openbow fiberglass.
1981 75hp Johnson seahorse
model: j75trlcim

I am looking for alittle more performance, it seems to be a little slow. is 75hp just gonna be a slow motor for this boat or re there things to make it a bit faster?

is there a prop for this engine that would make it faster while not breaking the pocket book?

would one of those stabalizer fins help speed or just time to plain?
 

walleyehed

Admiral
Joined
Jun 29, 2003
Messages
6,767
Re: what prob to use?

The fin is a tool that will shorten time-to-plane, but with a std engine heigth set-up, speed will be slower.
We can usually raise the engine on the transom and gain some speed/RPM...how far depends on the type of prop and just what you are looking for and how you use this rig.
 

greenleemm

Cadet
Joined
Nov 5, 2006
Messages
11
Re: what prob to use?

well this is my first boat and i guess i dont know how fast it should go.
my wife and i wanted something that would at least pull a tuber pretty good but the boat just seems pretty slow.
are there certain props that might promote faster speed?

the speed is fine for my solo use. (fishing) but when summer comes, my wife is going to want to have a couple with us a maybe pull a tube, but i am just not seeing this motor and able to do that. I was just expecting a little more from 75hp on a small 16 footer i guess.
 

walleyehed

Admiral
Joined
Jun 29, 2003
Messages
6,767
Re: what prob to use?

First thing would be to know for a fact that 75 is healthy.
A good, strong 75 on that 16ft'r will pull tree-stumps with the correct prop.
The method of determining the "correct" prop is to install a tachometer if you don't have one. The tach is the most important gauge in a boat.
Speed and pulling power don't really go hand-in-hand so you may require 2 props in the end...1 for fishing as you like to do, and 1 for towing/playing with the toys.
Do you have a tach?
Can you get any numbers off of the prop? you may have to remove the nut and washer to find the numbers, but they ARE there.
 

greenleemm

Cadet
Joined
Nov 5, 2006
Messages
11
Re: what prob to use?

i dont have a tach on the boat, i could prob install one after i find some info about how to do that. I wouldnt be able to get the prop number untill after work tomorrow
 

greenleemm

Cadet
Joined
Nov 5, 2006
Messages
11
Re: what prob to use?

oh i do have a tach, i was thinking speedometer. when i took it out on the first test run, it was sitting all open at around 5500
 

Ron G

Commander
Joined
Apr 28, 2005
Messages
2,905
Re: what prob to use?

You need to varify the tac and make sure it is right.
 

greenleemm

Cadet
Joined
Nov 5, 2006
Messages
11
Re: what prob to use?

ok well, I am going to want to have a tuneup done anyway because I dont know if the guy was lying about having one done. I am sure this is something i can ask the service guy to verify right?

for this motor out of curiosity do you think you might have a ballpark on a tuneup, verifying the tach, adding a speedometer and fixing the gas float because the stays full all the time and i know its not(built in tank)?

ive only been a boat owner now for 3 days and dont know about this stuff, just dont want to be aken at the shop.

or if anyone out here is in the sacramento ca area, know a honest boat mechanic?
 

walleyehed

Admiral
Joined
Jun 29, 2003
Messages
6,767
Re: what prob to use?

Depending on how they test the tach, it really needs to be checked at WOT.
It can be real close at 1000RPM but might be 200-400 off at Top-end (WOT), and that info will tell us what we need to do prop-wise.
 
Top