Fuel Consumption

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rick.jones wrote: Sounds like you have a too high pitch prop (a common problem). It's likely 13", 12" would allow higher revs at WOT.

Thanks Rick. I am pretty sure from markings mine is a 13. She is in the water in Weymouth at the mo and prop is on list to sort when she comes back home next month.

Over propped seems likely as it will spin up when driven on by a wave, but can't hold additional revs. I want to have a play with 60hp mod before I do anything else..

Hi Matt and Rick

Hi Matt and Rick

I had our Yamaha FT50 serviced just on Thursday. Using the data logger (a £15 extra) confirmed that the engine is now reaching 5000 to 6000 rpm at WOT. This is with the current propeller which believe is a 14inch diameter x 11inch pitch. (14 x 11K).

The engine was supplied by Richard Hallowes at Macgregor in Falmouth in 2008 with a 14inch x 13K. The data logger confirmed that with this propeller the engine never made it to 5000rpm - hence the prop change.

I suggest that the prop was chosen by Macgregor to give max speed with the boat lightly loaded and the ballast tank empty. However "warm water and likelihood of rescue high in the event of capsize" are more Californian conditions than the UK so we always have the ballast tank filled!

The propeller box advises that 1 inch pitch will affect engine revs by 200 - 300 rpm. Hope that helps!


Adrian Cox

Shema 2008 26M

I think Roly's 1 to 1.5 miles

I think Roly's 1 to 1.5 miles per litre is a good number.

In West Scotland, you should be aware that very few places now sell petrol (only diesel). Portavadie is one of the few that was still doing it last year. You need to take 2 or 3 10 litre cans in order to get from petrol stations onshore.


have had a great week out and

have had a great week out and around Weymouth

Quick update... I removed the air restriction insert, it made zero difference. I guess at 4600 rpm that I am getting air flow is already adequate. Any benefit would come at greater revs. Water ballast in with some chop.

Next step is to sort the prop size which won't happen until I pull her out the water so will prob be an update for next year now.