Folding Prop

[Cat 310 #1 in GA]

I have read most or all of the information in the forum archives about folding props and I wanted to post what I am considering to see if it makes sense. My Catalina 310 has a slightly undersized engine - it is a Yanmar 2GM20F which is 16-18 HP depending who you ask. Add to that the fact that I sail where there is strong tidal current due to 6-8 foot tides (S. GA/N. FL). My boat has a fixed 3 blade prop that is either 14 or 15 inches. The survey says 14" and I have never measured it so let's go with 14". When fighting the current I can barely go above 3.5-4.0 knots and if there is wind with it then 3.5 max. I am considering going to a flex o fold prop and they have recommended a 15x11-3R prop for my boat & engine. Am hoping it will increase boat speed under power (I know it will under sail) so I can at least have a fighting chance against the currents. Since the flex o fold people are very unhelpful and this is a big investment, I wanted to ask any of you who have switched to a folding prop if it did indeed increase boat speed under power? Can I reasonably expect 1/2 knot increase?
TIA,
bob

 

[LeslieTroyer]

In Yachting tests flex fold 2 & 3 bladed props were the fastest but only by 0.15 kts over a standard 3 blade. Varifold, autoprop and slipstream were also faster but not by much.

Sorry I don’t think you’ll get half knot under power using a folder.
http://www.yachtingmonthly.com/gear/folding-and-feathering-propeller-test-29807

 

[Gunni]

Can I reasonably expect 1/2 knot increase?

Not likely. Your fixed prop is optimized for your engine power band. You could play around with the pitch of a feathering prop but then you get into trouble with overloading your engine and causing it to run rich and carbon up.

 

[KZW]

I find it interesting that they recommended the same propeller, 15x11R two-blade for my Universal 25 XPB ( max. rated 26 hp / 3.200 rpm, gear reduction ratio 1:2,05)