Prop for my Johnson GT200

[Jwhit612]

I have a 20' Glastron bowrider with a Johnson GT200 outboard. The outboard has a 21 pitch, 14.25 diameter alumanim prop on it. When there is only 2 or 3 people in it, it will jump right up on plane with no problem. However, I recently had 10 people in it and it really struggled to get up on plane. Keep in mind, these were young high school kids, mostly girls, so it wasn't a tremendous amount of weight. then last week I had just two of us in the boat and one big guy on a tube behind it. It kept choking out when I would throttle up. I finally got it to stay alive but it really struggled to get up on plane. When I got rid of the tuber, I had no trouble getting up on plane again.
So I'm thinking I need to change out the prop if I'm going to be pulling skiers or tubers. Agreed?
Any recomendations on what prop to start with? I have a spare but it is a 24 pitch with a 14" diameter. I'm thinking that will be too much for it. I'm thinking maybe a 19 pitch?

 

[Banner Pub]

Re: Prop for my Johnson GT200

I have a 20' Glastron bowrider with a Johnson GT200 outboard. The outboard has a 21 pitch, 14.25 diameter alumanim prop on it. When there is only 2 or 3 people in it, it will jump right up on plane with no problem. However, I recently had 10 people in it and it really struggled to get up on plane. Keep in mind, these were young high school kids, mostly girls, so it wasn't a tremendous amount of weight. then last week I had just two of us in the boat and one big guy on a tube behind it. It kept choking out when I would throttle up. I finally got it to stay alive but it really struggled to get up on plane. When I got rid of the tuber, I had no trouble getting up on plane again.
So I'm thinking I need to change out the prop if I'm going to be pulling skiers or tubers. Agreed?
Any recomendations on what prop to start with? I have a spare but it is a 24 pitch with a 14" diameter. I'm thinking that will be too much for it. I'm thinking maybe a 19 pitch?

I'm no expert, but going to a 19 pitch is going in the wrong direction. I would try the 24 pitch that you have. If it is too much, you will need to go somewhere in between.

 

[Chris1956]

Re: Prop for my Johnson GT200

A 19 or 17" pitch prop is a better choice with more weight in the boat. Normally you will prop for average load. Realistically, I think you are propped to the max with the 21"pitch prop. A 19" pitch is probably the best choice for a 2-4 person average load.

 

[jestor68]

Re: Prop for my Johnson GT200

Does this boat have a tachometer? What rpm does it do at WOT? What speed? You prop a boat to turning within a certain rpm range at full throttle. We need to know that it order to say whether you have too much or too little prop.

"Choking out" when I throttle up sounds like it needs a tune up.

Read the "sticky"; "how to get the best results from your question" and provide as much of the info as possible. We have a bunch of programs and charts and other cool stuff that enable us to come up pretty accurate predictions provided we have some numbers to plug in to them.