The Perfect Prop

Discussions about Cape Dory, Intrepid and Robinhood sailboats and how we use them. Got questions? Have answers? Provide them here.

Moderator: Jim Walsh

Post Reply
Duane Yoslov

The Perfect Prop

Post by Duane Yoslov »

There's been a lot of discussion in the past about what the right prop is for CD33's/330's. The one that came with mine was fixed 2 blade 14"/10". This was grossly under powered for the 24hp Universal engine. I researched feathering props but it would have been difficult without modifying the prop apperature so I opted for a 3 blade fixed 14"/12". This prop will move the boat along at hull speed and for the first time, I've actually been able to steer in reverse! Anyway...thought you'd like to know.

Duane Yoslov
Mystic CD330
Sausalito, CA



yoslovd@aol.com
Chris

Re: The Perfect Prop

Post by Chris »

Duane - I have a CD330 which came equipped with a 10"RH12 prop. I have never noticed the clearance which the 10" propeller offers but assume I could fit a 14" if you can (great assumptions). Do you notice the engine straining as you increase RPM's? Have you experienced any problems maintaining the proper operating temperature?

I would love to get some sound advise on the pros and cons of a larger propeller. The only experience I have is aboard a friends boat who increased his pitch to such an extent that he could not reduce speed sufficiently, even at engine idle, for safe docking.

Duane Yoslov wrote: There's been a lot of discussion in the past about what the right prop is for CD33's/330's. The one that came with mine was fixed 2 blade 14"/10". This was grossly under powered for the 24hp Universal engine. I researched feathering props but it would have been difficult without modifying the prop apperature so I opted for a 3 blade fixed 14"/12". This prop will move the boat along at hull speed and for the first time, I've actually been able to steer in reverse! Anyway...thought you'd like to know.

Duane Yoslov
Mystic CD330
Sausalito, CA


Chris.reinke@transamerica.com
M. R. Bober

Re: The Perfect Prop

Post by M. R. Bober »

Our CD330 came with the same engine/prop combo. When we swapped props (this season) we were advised by the prop shop that adding a third blade generally meant keeping the same diameter and coming down 2" on pitch. When they found that our 2 blade prop was a "Columbian" they felt we could get by witha 1" drop(heavy blade, thick chord). The acid test was could the engine in forward gear come to within 100 rpm of its top speed in neutral? Sadly, in our case the answer was no. Prop will be swapped at next haulout



thebobers@erols.com
Duane Yoslov

Re: The Perfect Prop

Post by Duane Yoslov »

A 10"RH12 is grossly underpowered for the engine you have. Do you notice prop cavitaiton? The Universal M30/24hp wants a 2 blade 17"RH11. Obviously this will not clear in the apperature and 14" is about the maximum which leaves about 2" clearance on the rudder. Adding a blade does reduce the pitch or diameter by 1", so in theory a 14"RH12 is still under powered for the engine. This is true as I can still easily reach max RPMS of 2400.

I have found that the engine does not strain at all but have noticed the temperature gauge go up from where it used to be. This is a good thing as it would barely move before and it is no hitting the 140 - 160 range which promotes full combustion.

As for the concerns about safe docking, if the boat is moving to fast in neutral(I haven't found this to be an issue) - just put it neutral. More power means you can stop the boat BETTER in docking manuevers also.

Hope this helps...
Chris wrote: Duane - I have a CD330 which came equipped with a 10"RH12 prop. I have never noticed the clearance which the 10" propeller offers but assume I could fit a 14" if you can (great assumptions). Do you notice the engine straining as you increase RPM's? Have you experienced any problems maintaining the proper operating temperature?

I would love to get some sound advise on the pros and cons of a larger propeller. The only experience I have is aboard a friends boat who increased his pitch to such an extent that he could not reduce speed sufficiently, even at engine idle, for safe docking.

Duane Yoslov wrote: There's been a lot of discussion in the past about what the right prop is for CD33's/330's. The one that came with mine was fixed 2 blade 14"/10". This was grossly under powered for the 24hp Universal engine. I researched feathering props but it would have been difficult without modifying the prop apperature so I opted for a 3 blade fixed 14"/12". This prop will move the boat along at hull speed and for the first time, I've actually been able to steer in reverse! Anyway...thought you'd like to know.

Duane Yoslov
Mystic CD330
Sausalito, CA


yoslovd@aol.com
Post Reply