Question about buying a prop

[mdg12345]

I have just rebuild a 1969 17' Glastron boat and had to add weight because of a rotten floor, seats ect. I put on a used 1975 Evinrude 75 Hustler outboard on. I am told that the pitch is wrong on the prop. I was looking on iboats.com but I don't know if I have a small or large gear box. I have no tach because it was not in the original plans for that year. Right now I have a 13 3/4 X 15 prop. When I am out by myself I can hardly plan over, but if there is two people in the boat I might as well give up. The last time I ran it was at the end of last season. I got it tuned up and he told me that I needed to break it in so I ran it some more. Then I told him what it was doing and we tested it in a tank of water and it sounded great but when I put it back on the boat some problem. Can you help me out.

 

[Moving Target]

Re: Question about buying a prop

With out a Tach its pretty hard to get the right pitch. And are you sure the motor is running right? How and when did it run last?

 

[Specks n Reds]

Re: Question about buying a prop

 

[SCO]

Re: Question about buying a prop

What size and model is the glastron?

 

[Spidybot]

Re: Question about buying a prop

If it has a hard time getting on plane with a 15" changing to 17" will only make things worse.<br /><br />Get a tach (borrow?), find out what you acchieve at WOT and check a prop selector for comparison. If you are close to the recommended pitch and still do not get the right rpm your motor may not be running as supposed.<br /><br />If the motor is OK you have to change pitch, using the rule '1 inch pitch up means 200 motor rpm down and vice versa'.<br /><br />One of many prop selesctors can be found here at Merc's

 

[SCO]

Re: Question about buying a prop

Oh, I see you said 17'. Mine is a 17.5 footer and takes a 135 hp motor. You might be minimal on the hp. You can check the classic glastron site and get the recommended motor hp range for that boat if they have the brochure for it.