Need some advise on props. I have a Hunter 336 with a yanmar 3gm20f. The prop is a factory 16x13 2 blade. I can push her under power to 6 notes. The problem is going in and out inlets and through bridge openings durning max current in Florida. With a 4 to 5 know current, I can get a 1-2 knot forward COG. Sometime thought the bridge openings, I can almost get stuck!!. The bottom and prop are clean, but is there a way to get more then 6 knots out of a 336? Should I go to a bigger prop or 3 blade?
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3 blade will help!
Mickey: I think that a three blade prop would help. You may want to also consider having your prop reworked by Bay Props in Alameda, CA. They put winglets on the prop which keep water from slipping off the tip. You may be limited as to the size of the prop that you would use on your boat because of clearance between the prop tip and the hull. They also can put these non-slip tips on a new three blade prop which may be the real deal.
Mickey: I think that a three blade prop would help. You may want to also consider having your prop reworked by Bay Props in Alameda, CA. They put winglets on the prop which keep water from slipping off the tip. You may be limited as to the size of the prop that you would use on your boat because of clearance between the prop tip and the hull. They also can put these non-slip tips on a new three blade prop which may be the real deal.
Mickey, Steve makes a good suggestion...
Before you make the jump, however, talk to your local prop shop. They need to know several things about your boat, e.g., engine model, horsepower rating, prop size, displacement, etc. They can help you determine whether your prop is the right size for your boat. What is the maximum rated RPM for your engine at idle, according to your owner's manual and can it attain that RPM? Next, what is the maximum RPM in forward gear? Your engine should reach to within 100 to 200 RPM of its maximum rate at full throttle. You can do this without harm to the engine, but warm it up first. Do these things to rule out fuel, intake air or exhaust flow problems. Your engine and prop should be set up to push your boat to hull speed, whatever that is. Six knots is pretty close to hull speed I suspect. We have similar problems in the San Juan Islands where tide currents can get very strong. Here we time our passage through these narrows and passes at slack water. Terry
Before you make the jump, however, talk to your local prop shop. They need to know several things about your boat, e.g., engine model, horsepower rating, prop size, displacement, etc. They can help you determine whether your prop is the right size for your boat. What is the maximum rated RPM for your engine at idle, according to your owner's manual and can it attain that RPM? Next, what is the maximum RPM in forward gear? Your engine should reach to within 100 to 200 RPM of its maximum rate at full throttle. You can do this without harm to the engine, but warm it up first. Do these things to rule out fuel, intake air or exhaust flow problems. Your engine and prop should be set up to push your boat to hull speed, whatever that is. Six knots is pretty close to hull speed I suspect. We have similar problems in the San Juan Islands where tide currents can get very strong. Here we time our passage through these narrows and passes at slack water. Terry
Mickey /3 blade prop
Mickey, I also have a 336 and I installed a three blade prop last season. I have a 3 blade 16X12 Michigan "Sail" (fixed blades) It cost just under $500 with tax. I an very satisfied with it an it has done exactly what I wanted it to do. I went to a local prop shop and we ran all the info into his computer system and came up with the correct size and pitch.We chose the Michigan "Sail" type because it appeared to be a good comromise for performane with less drag then the nornal three blade.Let me caution you it will not make your boat faster as boat speed is a factor of hull speed but what it will do is give you more thrust and that will give you a more constant speed and some more punch against waves,currents etc,it will also give you an amazing difference in how smooth the boat is under power, you will be able to run slightly lower rpm and have same boat speed as before but the whole drive train smooths out and has much less noise and vibration.(this was my original reason for going to a 3 blade)I would caution about going to a larger prop (2 or 3 blade) as you must match the prop to the engine & trans or you will be overloading the engine by just going to a larger prop size.Before everone starts about 3 blade having to much drag let me say that I don't race and drag is not a issue for me,however I did not notice any difference with the 3 blade vs. the 2 blade, If you are a avid racer you may want to consider a folding or feathering prop,be aware of big big cost difference.Appx 2 grand more for a feathering 3 blade.I would suggest that you try a three blade,I am very happy with mine and it sounds like a three blade will be a big help in you situation of currents and bridges
Mickey, I also have a 336 and I installed a three blade prop last season. I have a 3 blade 16X12 Michigan "Sail" (fixed blades) It cost just under $500 with tax. I an very satisfied with it an it has done exactly what I wanted it to do. I went to a local prop shop and we ran all the info into his computer system and came up with the correct size and pitch.We chose the Michigan "Sail" type because it appeared to be a good comromise for performane with less drag then the nornal three blade.Let me caution you it will not make your boat faster as boat speed is a factor of hull speed but what it will do is give you more thrust and that will give you a more constant speed and some more punch against waves,currents etc,it will also give you an amazing difference in how smooth the boat is under power, you will be able to run slightly lower rpm and have same boat speed as before but the whole drive train smooths out and has much less noise and vibration.(this was my original reason for going to a 3 blade)I would caution about going to a larger prop (2 or 3 blade) as you must match the prop to the engine & trans or you will be overloading the engine by just going to a larger prop size.Before everone starts about 3 blade having to much drag let me say that I don't race and drag is not a issue for me,however I did not notice any difference with the 3 blade vs. the 2 blade, If you are a avid racer you may want to consider a folding or feathering prop,be aware of big big cost difference.Appx 2 grand more for a feathering 3 blade.I would suggest that you try a three blade,I am very happy with mine and it sounds like a three blade will be a big help in you situation of currents and bridges
I also went with a Michigan sailor
fixed three blade.. and like Pete said better thrust thru waves and currents.. and MUCH smoother.
fixed three blade.. and like Pete said better thrust thru waves and currents.. and MUCH smoother.
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