20' bayliner capri w/ 120 force. what prop?

JTRUSH

Seaman Apprentice
Joined
Oct 14, 2008
Messages
46
what prop should i use for a 1990 bayliner capri with a 120 force outboard.
thanks
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: 20' bayliner capri w/ 120 force. what prop?

JT, welcome to Iboats prop forum and we will try to help you as much as we can, but there is certain information that is needed in order to help you. Working over the internet and not being able to see the boat or prop the question is about, and most people don?t know the make and model of the prop, makes it much harder to propose a solution to the correct prop that you need. When we get information in bits and pieces we are continually having to look back and forth to try and piece the information together. The following form has all of the information that is needed to help you with your problems in finding the right prop. If you do not know all of the information that is asked for on the form please give us the most information you have available as I have a program I designed to find the right prop for any planing hull boat that needs this information. It requires time to find all this information when we have to look for it and in my defense I expect you to be willing to expend as much effort in finding the right prop as I do. We hope to be able to help you get the best prop we can for your particular uses, and this information is required to do that.
It is not as simple to pick the right prop as most people coming to this forum think it is, that is why we ask so many questions, it is for your benefit we ask all these questions. And if you have a stainless steel prop or are changing to one the blade geometry of the prop can make a lot of difference in speed and RPM. ALL of my calculations are done assuming an aluminum 3 bladed prop will be used, when changing to a SS prop or changing within SS props or we need to discuss what you are trying to accomplish.

Iboats Boat and Motor Info

1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make and model of motor
7. HP and gear ratio of motor IMPORTANT
8. Manufacturer?s recommended WOT range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
10. Is it a bass boat or does it have a pad bottom
11. Does it have a hydrafoil or trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop
13. WOT RPM and speed from prop, how much gas and how many people in boat for test data
14. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations

REMEMBER, The numbers I give you will be NO better than the information you give me

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.

H
 

countvlad

Chief Petty Officer
Joined
Jun 29, 2009
Messages
439
Re: 20' bayliner capri w/ 120 force. what prop?

what prop should i use for a 1990 bayliner capri with a 120 force outboard.
thanks

i wish things would be that easy... we need more info.... what is the manufact rec WOT range??? what is your current WOT ???

my guess is you're running either a 15 or a 17 pitch.....
 

junior1113

Senior Chief Petty Officer
Joined
Jan 29, 2009
Messages
763
Re: 20' bayliner capri w/ 120 force. what prop?

how can you guess on a prop size with the year of the boat and a motors hp. lol could be a 15' or 21' boat.
 

countvlad

Chief Petty Officer
Joined
Jun 29, 2009
Messages
439
Re: 20' bayliner capri w/ 120 force. what prop?

how can you guess on a prop size with the year of the boat and a motors hp. lol could be 15' or 21'

:) i never said it was 15 or 21 .... i guess i had 50 50 chances hahaha reason why i have almost a similar setup... thats all
 

JTRUSH

Seaman Apprentice
Joined
Oct 14, 2008
Messages
46
Re: 20' bayliner capri w/ 120 force. what prop?

i only have a gas and speed gauge. how do i know the rpm's?
 

junior1113

Senior Chief Petty Officer
Joined
Jan 29, 2009
Messages
763
Re: 20' bayliner capri w/ 120 force. what prop?

i would invest in a tach. how do you know if your lugging or over reving? motors have a recomended wot rpm range to ensure motor life. answer all other questions and hwsii can choose a prop to fit your motor and boat weight.
 

countvlad

Chief Petty Officer
Joined
Jun 29, 2009
Messages
439
Re: 20' bayliner capri w/ 120 force. what prop?

i only have a gas and speed gauge. how do i know the rpm's?

TACH very important.... we cant answer your questions without a tach... and also it will help you out in the long run.... good luck
 
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