tracker avalanche prop size???

[03avalanche]

hey all, hoping someone could help me with a couple questions. i have a 2003 tracker avalanche with a 2003 mercury 115 four stroke efi. i know this boat is under powered but i just want to make sure i am getting all that i can out of it!! i have read where some people are claiming to get 45-50 mph with same boat and motor and i just dont see it. my boat runs gps 38 mph at 6000-6100 with a 19 pitch prop. runs 6100 with myself and 6000 with partner and live wells full. thought about going to a 20 pitch but was hoping to find out more info before purchasing one. very slow to get up on plane when live wells are full with 19 pitch thought it would get worse with a 20 pitch. how do you know if your motor is set to the right hieght?? any and all comments are welcome!!

 

[steelespike]

Re: tracker avalanche prop size???

Set up right I wouldn't call it under powered.38 is respectable I've seen lots of reports of boats up to 1900 lbs with 115 motors running 37 with a little over 4 second hole shot.(2 stroke)
Four stroke motors can sometimes struggle for good hole shot.gear ratio is 2.07 .
If your prop has a lot of bow lift it would slow hole shot but improve speed.
As for height; your antivent plate(just above the prop) should be even with or slightly above the bottom of the boat.I usually suggest raising it to a point just before venting(cavitation)
becomes a problem. You can measure by laying a straight edge along the keel to the antivent plate.The higher the motor the less drag.It can improve speed and hole shot.
Eliminate as much weight as possible at the stern,
4 blade props can improve hole shot and low to mid range performance.I think on your setup I would go with the same brand,style and pitch.

 

[03avalanche]

Re: tracker avalanche prop size???

thanks steelespike!!! i was beginning to wonder what i could possibly be doing wrong for my boat not to be running those speeds. i keep all gear loaded at bow with only light items at stern, the prop i have now is an old michigan prop, still shiny and new with no nicks, do you have any insight on what 4 blade prop would have good bow lift that would possibly be the best choice?? i do not have a local prop shop to help suggest props just boat sales people who always say they are not really sure.

 

[steelespike]

Re: tracker avalanche prop size???

If you can find good prop shop within a reasonable distance they may be able to tweak your prop to improve hole shot without losing rpm and speed.
I can only work in generalities. I don't have info on the finess of prop design. Typically when going to a 4 blade they suggest a 1" pitch reduction to help keep the rpm up.Your motor runs a little high so you may be able to forgo the pitch reduction.Also it is usually suggested to stay with the same brand and material to get more predictable results.
Do you trim in(down) for hole shot?From your description I assume your prop is stainless.
If it is ss you should stick with ss.to get more predictable results.Before any prop changes check your height.If you're fighting hole shot you don't want a prop with lots of bow lift.
The 4 blade props generally have more stern lift this helps hole shot and planing at reduced speed.A 4 blade may reduce your top speed slightly.Its difficult get hole shot and top speed with the same prop.