Hello I am the proud new owner of a 85' Catalina 30 with a Universal M25 motor. My boat seems very underpowered with the factory 2 blade prop in chop and current. Note my prop and hull our cleaned regularly. I have an extra 3 blade prop that came off and Endeavour 32 that is 14 x 14. I have been reading the forums about the right size 3 blader and seems like 13x13 is pretty standard. Will my 14 x 14 work for my boat or get me by until I can afford a 13 x 13?
14x14 3 blade prop catalina 30
- Thread starter ScottNeely
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Prop size
The general rule is going from a 2 blade to a 3 blade is to go down at least one inch in pitch. So you would need a 13x12 or less. Also, you might not have enough prop tip to hull clearance with a 14. I think you would overload the engine and have even less power. Maybe someone else had tried it, Just my .02.
The general rule is going from a 2 blade to a 3 blade is to go down at least one inch in pitch. So you would need a 13x12 or less. Also, you might not have enough prop tip to hull clearance with a 14. I think you would overload the engine and have even less power. Maybe someone else had tried it, Just my .02.
My '91 Cat30, with an M25xp uses a three blade 13x10 prop. In a 4 knot current, I make 5.5 knots at 2800rpm. I would expect that's about optimum. Good Luck, Happy Sailing and Happy Thanksgiving.
Those prop sizes sound pretty big to me.
I have the Atomic 4 which is somewhere betwen 20 - 30 HP.
I bought a 12" x 6" 2 blade fixed prop from a C30/Atomic 4 owner for my own boat. I had it changed to a 13" x 8" for my own boat.
On the C 30 the prop is in good, undisturbed water but on my boat the prop sits in an aperture. I need a bigger prop then the C30's can get away with.
I would think that in a 3 blade prop an 11" x 6" prop would be fine.
I have the Atomic 4 which is somewhere betwen 20 - 30 HP.
I bought a 12" x 6" 2 blade fixed prop from a C30/Atomic 4 owner for my own boat. I had it changed to a 13" x 8" for my own boat.
On the C 30 the prop is in good, undisturbed water but on my boat the prop sits in an aperture. I need a bigger prop then the C30's can get away with.
I would think that in a 3 blade prop an 11" x 6" prop would be fine.
Engine information for you:
http://www.c34.org/wiki/index.php?title=Main_Page
Scroll down to engine & fuel.
Congratulations on your new boat.
http://www.c34.org/wiki/index.php?title=Main_Page
Scroll down to engine & fuel.
Congratulations on your new boat.
14X14 would seem to be a rather huge jump. Considering that the largest pitch offered for a C-30 is a 12 pitch. As far as the diameter fitting or not. I would guess that if a 14 inch diameter were the hot set-up, it would be standard issue. Finally, the shaft diameter would need to looked at as well. Excess torque make be another concern on the cutlass and bearing.
I run a 13X10. It moves the boat over 7.2 mph at 2800rpm in calm water. And almost that as well with wind and waves.
Thinking about "hull speed", and getting over your own wake. You cannot make much more speed then that without the boat acting squirrelly.
I would not want to be without the three blade when motor-sailing, or when I want to make way in high waves.
I run a 13X10. It moves the boat over 7.2 mph at 2800rpm in calm water. And almost that as well with wind and waves.
Thinking about "hull speed", and getting over your own wake. You cannot make much more speed then that without the boat acting squirrelly.
I would not want to be without the three blade when motor-sailing, or when I want to make way in high waves.
Scott,
I'm afraid that the 14x14 isn't going to work in your application for at least two reasons: (1) The diameter is too large (2) The pitch is too great.
I had an M25XP on my 1987 Catalina 30 and for a while I had a 3-blade 13x13 and it was just right for that engine/transmission combination. (The M25XP has a few more HP than your M25.) The diameter is limited by the need to clear the hull (obviously), and for a prop with a normal hub you are looking at 13" max. I did switch later to a Martec 2-blade folder that was 14" diameter, but that was possible because it had an elongated hub that set the blades farther aft than on a standard prop. For the kind of prop you are talking about you're limited to 13". So that really ends the discussion right there.
Even if the diameter were not too large, the pitch would not be correct anyway. For a given diameter the pitch is a function of the engine HP and transmission ratio. You should contact a prop shop that specializes in this kind of thing and they can run the calculations for you and tell you what is appropriate for your particular engine and transmission combination. Comments from others about what they use are meaningless unless they are using the exact engine and transmission that you are using.
Hope this helps,
Alan Gomes
Our 1983 C30 has the factory supplied 13 x 10 three bladed prop being pushed by a M25 (21 hp) engine. It is ideal for our area (Gulf Islands), numerous passes with strong currents and many long narrow bodies of water where the wind and waves have considerable fetch. Normal cruising speed is 5 to 5.5 nm/hr.
I think that you've been given good advice about 14" diameter being too large a prop.
We've all had many discussions about this, and I've also wanted to switch my 2 blad to a 3 blad for more oomph. I have the tiny 5411 which works ok in calm water, but stiff chop will slow her to a crawl. Although I've worried about overloading the engine & trans. in a 30 year old boat more then gaining speed. I've also heard many times that the small gain under power with the extra blad will be the same speed lost under sail with the additional drag. As we are primarilly sailors not power boaters, it seems that its more important to sail more efficiently then motor. This is the eternal dilemna, unless you fork out the bucks for a folding 3 blade prop, but then you have the extra moving parts in the prop to maintain. My 2 c.
We've all had many discussions about this, and I've also wanted to switch my 2 blad to a 3 blad for more oomph. I have the tiny 5411 which works ok in calm water, but stiff chop will slow her to a crawl. Although I've worried about overloading the engine & trans. in a 30 year old boat more then gaining speed. I've also heard many times that the small gain under power with the extra blad will be the same speed lost under sail with the additional drag. As we are primarilly sailors not power boaters, it seems that its more important to sail more efficiently then motor. This is the eternal dilemna, unless you fork out the bucks for a folding 3 blade prop, but then you have the extra moving parts in the prop to maintain. My 2 c.
I'm seriously thinking about the 15 x 11 extendoprop...something to consider.
http://mysite.verizon.net/resqp86c/performancepropellers/id33.html
http://mysite.verizon.net/resqp86c/performancepropellers/id33.html
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