Prop Sizing and Placement

[GregH]

That does not sound good at all. The engine appears to be some combination of low on power and/or severely over-propped. You essentially have about a 10 HP engine right now.
I would first off get a manifold vacuum gauge and do a compression test and then think about an Indigo prop or maybe a 12x6 two blade if you race.

My plans is the Indigo 3 blade for next spring. I'll do a compression test as it's been 3 years since the last one, when I picked up the engine. The vacuum gauge hovers around 15 at idle and I have to check what it says at "cruise". Last Aug when I first installed it, it would read zero at 'cruise"

[Dave Neptune]

Greg, my ole E-35 MKII idled at about 15" of vac but at cruise I got 2100RPM's @ 6~7" of vac with the Indigo. I could go much harder when necessary but why bother as I was getting 6.2 kts with a 25'6" waterline.

Your engine is lugging bad if you are at anything under 4" @1450RPM's, IE only about 10HP. With the Indigo I could get 25~2600 wide open or about 25HP. I would guess the cruise load to of been around 15HP or just about a gallon an hour. Load duty gas engines make around 2HP per pound of fuel per hour when running well.

Dave Neptune

[GregH]

Your engine is lugging bad if you are at anything under 4" @1450RPM's, IE only about 10HP. With the Indigo I could get 25~2600 wide open or about 25HP. I would guess the cruise load to of been around 15HP or just about a gallon an hour. Load duty gas engines make around 2HP per pound of fuel per hour when running well.

Dave Neptune

Thanks for the info; though not much I can do this season.