Bass Boat (1997 Astro 1700) Prop Help...

[HammytheFisherman]

Hey fellas. I currently have a used 1997 Astro 1700 bass boat that is 17' with a 1997 Mercury ELPTO 115HP on the rear. I am currently running a Merc Laser II SS 22P prop and turn roughly 4800RPM's at WOT and the engine plate states the max RPM's to be 5250. The engine seems to be mounted at the correct height and when properly trimmed and fully loaded, I achieve 45-46MPH WOT according to GPS.

I've spoken with other boaters who seem to get in the mid 50's with their 115's WOT. What numbers are others with 115's turning? I have been thinking about dropping to a 20P prop to see if that can give me the extra 400RPM's I need to reach my engines max RPM rate. Does anyone have any specs on this particular motor or boat that might help steer me in the right direction. Its not a huge deal, but I feel as though I am losing 5-10MPH due to my prop. If not the prop, then I have no idea what could be causing the speed loss.

Any suggestions on the prop change or other help? Or is anyone else running the same engine that can give me an idea as to what MPH I should be achieving. Thanks!

 

[gcboat]

Re: Bass Boat (1997 Astro 1700) Prop Help...

Hammy,
I think going down to a 20 pitch will let you pick up that 400 rpm's. General rule of thumb is for every degree of pitch change there will a 200 rpm difference. Before you spend big bucks on a new one maybe a friend might have one you could try? Just a thought .

 

[steelespike]

Re: Bass Boat (1997 Astro 1700) Prop Help...

First thing I notice is the 1700 is rated at 90hp.and 1600 lbs I believe including the 90.A 115 is probably 50 to 100 lbs heavier.Don't assume your setup is right starting with the antivent plate even with the bottom raise the motor a hole at a time to a point just before venting becomes a problem.Under ideal conditions you could gain 2 to 3 mph and some rpm.Do it your self and no cost.Then you can make a decision on a prop.

 

[HammytheFisherman]

Re: Bass Boat (1997 Astro 1700) Prop Help...

I'm going to take a look at the motor height the next chance I get. I have a general rule of thumb of where it "should" be, so we will see how far off it is from that. If I can find someone with a 20P prop to play with then I will try that... def don't want to dump the cash on another prop if its not needed.

Without a motor holder/lift, how would I be able to do this on my own? I figured I'd have to have a shop do it due to the weight of the motor. I'm in the process of selling a couple old things around the house, so I might take that extra money and put it towards a manual jack plate which would give me 5" or so of play with the turn of a socket wrench.

Thanks for the replies.