Need info on Hunter 33 3 blade prop

[Ziya Gun]

Hello again BBThank you for your previous replies. I am the one who had an old Hunter 33 '80 in bad shape, had the engine rebuilt and the cracked 2 blade prop replaced with a 3 blade prop. Now I max out at 2000 rpm and I am convinced that I am over propped. I like the feel of a 3 blade prop, but which one shall I buy, I don't want to spend $2K, but I don't want to burn out my newly rebuilt engine either.Here are my specs;Boat: Hunter 33 '80 Engine Yanmar 2QM15 15 hp dieselStock prop: 14 x 12 2 blade weight: 10600 lbs LOA: 32'8" LWL: 27'1"Beam 10'2" Draft 4' Gear ratio 2.14 / 2.83 (not sure why) forwardrev: 3000 crankshaft Prop shaft 1400/1060 (???) What kind of a 3 blade prop do I need and where can I get one?

 

[Steve Dion]

You've got a 3 blade.

Ziya:You have a 3 blade prop. So the most inexpensive way is just to re-pitch this prop. Now the problem. This prop is over pitched by probably 4-5 deg. and depending on the prop you probably cannot take that much out of it maybe only 3 deg which is going to give you 600-800 rpm. You should have a diver pull the old prop and see what you are working with before you make any other decisions. If the prop is correct you could have some other problems.You really should read Justins post from earlier today regarding what to expect about the difference between a two vs three blade prop.

 

[Tim]

Options

Here's what I would consider:1. Keep what you have. Go slow and clean the mixing elbow every season. $0.2. Call Michigan Wheel and get a prop recommendation. Check the yellow pages for a prop shop and call around for a used prop. Expect to pay ~$200.3. Call Michigan Wheel. Order a prop from Defender. Expect to pay around $350.4. Call Cruising Design Inc and order a 3 blade feathering prop. Around $1100.

 

[Kevin L. Woody]

Right prop

Dear Ziya:Thank you for your note. What you are describing points very heavily to the propeller being overpitched. If you have your current propeller removed from the boat you can have it re-pitched. The re-pitching can easily take place at any prop shop capable of repairs. The amount of pitch reduction will be based upon the current propellers configuration. F.i. If the propeller was built as 14 x 12 and was re-pitched to a 14 x 10 to meet your current configuration, it may only have 1 to 2 inches of additional pitch adjustment. The repair shop will determine that. If there is not enough pitch adjustment left you may need to purchase a new fixed blade. What pitch you say? For every 1” of pitch removed you can anticipate apx. an 12% increase in Rpm’s. example: 2,000 x 1.12 = 2,240 new Rpm at new 1” less pitch setting. And so on there after. With your current setting I would think that you would need to remove apx. 3”of pitch. This should allow the engine to obtain apx. 2,809 Rpm’s. The reduction gears you listed are the two reduction gears available. If you need to know the installed reduction just look at your engine plate and it will be listed as IA: XX IB: XX. IA: being your forward gear and IB: being your reverse gear. I Hope this all helps.Sincerely, Kevin L. Woody