first post as iboat member.... prop question

[xkdxdavis10]

Hi iboats

I have a prop question. I have done research and decided I need a 15 pitch prop. but money is tight and I want to double check. I have a 1988 15foot fiberglass center Conso lewith a 1978 merc thunder 700 70hp.

 

[xkdxdavis10]

Re: first post as iboat member.... prop question

Some more info.... I want a aluminum prop and there is currently a 16 pitch prop but its destroyed beyond the. point of testing performance. the boat is a 15foot 88 fiberglass pacer.
I took the boat out once before purchase and with 2 people with a combined weight of 325lb the boat hit 5000 rpm with a added 200 lbs the boat hit 4000 and would not go higher the prop has damage on all fins and one has a Hal dollar size chip, it looks like a byte was taken off.

 

[steelespike]

Re: first post as iboat member.... prop question

It appears to me that a 16 is too much prop. Unfortunately without a good base line test its difficult to estimate a prop.
You can probably get the 16 repaired and have them repitch it to a 14. Get an estimate and compare it to a new 14.
If a 14 is too light you can still use it and just watch the rpm.It should improve your power.
Being over propped at 16" puts added stress on the motor besides the poor performance and poor mileage.
For a base line we need reliable rpm and gps speed.Some cells have a gps app.
Unfortunately even numbered props are harder to find.

 

[xkdxdavis10]

Re: first post as iboat member.... prop question

Thanks for the info. Do you agree I should be around 30mph? And maybe 26mph with a load of three adults.

 

[steelespike]

Re: first post as iboat member.... prop question

It does seem the boat should plane easily with 3 adults.And 30-35 mph seems possible.Results adding people is difficult to estimate.
Good balance is important are tanks and battery(s) in the stern?

 

[xkdxdavis10]

Re: first post as iboat member.... prop question

The two batteries are in center console. I have a 10 gallon tank that is always f
ull and a 2.5gal spare.