Starcraft Islander Prop

[skeetshooter]

Boat- 2002 Starcraft Islander 221v, 4.3L 190 hp, Alpha 1 with 1.81 gear. 9.9 four stroke kicker and fishbox cooler mounted on swim platform.

Uses- Fishing Lake Erie

Old Prop- 14.5x19 Black Max 3 blade WOT 4200-4250 at 42-43 mph. This prop had no bite at all. Boat had no grip on the water even in full down trim. Ran bow high and wallowed 8-9 mph until 3200 and then nosed down to plane speed at 26 mph

Current Prop- Diamond 4 14.5x18p WOT trim up 4350-4400 at 36 mph
WOT trim down 4150-4200 at 31-32 mph. Much improvement here as boat is gripping the water better and low speed handling are greatly enhanced. Runs real smooth at a 3800 rpm cruise in the 25-28 mph range. Runs off plane at 15-16 mph in the 2600 or 2700 range.


All this being said can I get more here? It has been recommended to me by some knowledgeable people to go to Powertech ELE4 15x17 , Solas Amita 4 14.5X17. Mercury prop program lists my current prop if I put in 4400 WOT rpm and a Alpha 4 15x16 if I put in 4300 RPM WOT. I was leaning toward the Powertech but would like to pontificate a little Any thoughts ?

 

[skeetshooter]

Re: Starcraft Islander Prop

According to the prop slip calculator I'm at 12-13% slip with the Diamond 4.
What would be a average to good slip number in a stainless prop?

To me on first glance the Amita 4 14.5x17p looks perfect if it is fairly equivalent to the Merc prop in design, maybe more lift ? Anyone compared these 2 props ?

Would the 15x17p ELE4 stainless even give the boat more grip on the water than the
aluminum props? Less slip at low speed, at WOT ? Better low speed control ?


If I went the Alpha 4 15x16 and gained 400 rpm for pitch drop and lost some RPM for diameter change should put me in the sweet spot ?
Any effects from increasing diameter from 14.5 to 15? Less slip ? Better hole shot? Lower planing speed ? Little effect at all ?


Am I trying to shave this to fine here and just have to try them?


Thanks

 

[steelespike]

Re: Starcraft Islander Prop

Diameter usually doesn't affect performance directly.Diameter goes up as pitch goes down.I've seen lots of excellent results on here with the Solas Amita 4 blade.
And they are usually very predictable on a planing hull.
Generally when prop slip reaches 15% they consider a prop change.
imo prop slip calculation accuracy is highly dependent on accurate input.
ss prop can give an overall improvrement including slip.However results could vary
from a few tenth to a few mph.

 

[skeetshooter]

Re: Starcraft Islander Prop

Thanks for the reply.

I went ahead and ordered the Amita 4 14.5x17 here at iboats
its a great deal and I will still consider a stainless anyways after I get some
numbers on the new prop. If I can get just 10-15% better low to mid speed handling than I'm getting now it will be well worth the money. Slogging head on 6-7 miles in 3-4 footers ain't fun
in a well behaved boat let alone one with control issues. Once I get the best prop on it then I will visit the trim tab market if I have to. It seems like you try to find the soundest boat you can get and then drill it full of holes