Pitch to high?

[86RinkerV153]

Repowered my 15' runabout with a Honda BF60 and took it to a mountain lake at about 7000' altitude this past weekend. The dealer set it up with a 11" prop with 14" pitch. We had 4 adults in plus some gear and I was pretty surprised at how hard it was to get it on plane. Into a fairly strong headwind at times it wouldn't even get on. The Yamaha 40hp that was on it before seemed to do better with a similar load at sea level, can't remember what prop was on it though. So I'm thinking one of 3 things or a combination:

• ​The altitude was killing my engine power; I've read that it was likely down 20%. For this altitude the pitch should be lower.
• The prop pitch was too high for this load, even at sea level and not related to the high altitude. A new prop with lower pitch is needed for this load even if I use it at sea level.
• The diameter should be changed. I don't really think this is the case but thought I'd throw it in for commentary.

This is my first boat and I'm very inexperienced with this sort of thing. Any expert opinions appreciated.

 

[Sea Rider]

Boating at high altitude levels is much different than at sea level, less air. Need to install an induction tach and check max achieved wot rpm with given load, OB is surely revving towards the lugging side. which is bad. What you can do for the moment is leave current prop for sea level use, tach it later and concentrate on at least 2-3 less pitch sizes for altitude boating.

At 7 K Feet, OB has already lost 40% of it's rated HP. Won't run top, but at least much better. Need 2 props, sea level and high altitude boating, each doing its homework.

Happy Boating

 

[QBhoy]

Was the yamaha 40hp a 2 stroke ? If so, here is a fair old weight difference between this and the 60 4 stroke. Prop experiments seems the way to go.

 

[Sea Rider]

Prop experiments seems the way to go.

Ideal is a carb rejet along a less pitch prop maximization, but a real PITA swapping jets back on/off everytime combo travels from sea level to high altitude and vice verse. Unless counting with 2 carbs jetted for both boating scenarios along 2 different pitched props, To each carb, its own prop..

Happy Boating