I've been luck enough this season to not have much time under power on my 320 but when I do fire up the beast it is unable to push me along anywhere near hull speed. I have the standard prop - would a three blade or something fancy help? I am VERY pleased with the handling characteristics of the boat around the marina so I definitely do not want to adveresly affect that by changing props. Thanks
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Which engine?
We would be better able to help if we knew what engine model you have as well as specifics on the Prop. It hard to say what isreally "standard". I assume that your bottom is reasonably clean and that you have taken a jump overboard and inspected the prop.... like no plastic bag is coiled on it and that you have no baracle colony living on it- they can really change the benefits of your prop. So let us know the specifics. Jim McCue
We would be better able to help if we knew what engine model you have as well as specifics on the Prop. It hard to say what isreally "standard". I assume that your bottom is reasonably clean and that you have taken a jump overboard and inspected the prop.... like no plastic bag is coiled on it and that you have no baracle colony living on it- they can really change the benefits of your prop. So let us know the specifics. Jim McCue
Me too...
I get about 4.5 - 5 knots max. However, I discovered that the engine was severly out of line requiring new mount holes to gain the necessary adjustment. This was fixed today so hopefully I can turn 3-4k rpm's without the engine sounding like it going to throw itself out of the engine room. If I still can't get at least 6 knots then I am going to look at props. Boat has 2GM20F Yanmar with a KM2P Trans Ratio = 2.21 F 3.06 R. Prop shaft is 1" I think. Rotation clockwise.
I get about 4.5 - 5 knots max. However, I discovered that the engine was severly out of line requiring new mount holes to gain the necessary adjustment. This was fixed today so hopefully I can turn 3-4k rpm's without the engine sounding like it going to throw itself out of the engine room. If I still can't get at least 6 knots then I am going to look at props. Boat has 2GM20F Yanmar with a KM2P Trans Ratio = 2.21 F 3.06 R. Prop shaft is 1" I think. Rotation clockwise.
New Prop . . . . consider Maxi and adjust
If you decide to get a new prop, get a Maxi prop. These can be adjusted to your liking so that if the pitch is too little and you aren't reaching hull speed while the engine revs, you can increase the pitch, or visa versa. There is even a model that can be adjusted while underwater. I have a two blade maxi on my 340 and love it. However, if you want a really smooth ride, by the 3 blade maxi. But considering you have a two cylinder engine, it might not be as much help as it would be on the a three cylinder unit. Cost = about 2 boat units for a 2 blade, 3 boat units for a 3 blade. See PYI for exact numbers. No I am not a dealer. Just a satisfied customer. Note, a boat unit is equal to $1,000. Jim
If you decide to get a new prop, get a Maxi prop. These can be adjusted to your liking so that if the pitch is too little and you aren't reaching hull speed while the engine revs, you can increase the pitch, or visa versa. There is even a model that can be adjusted while underwater. I have a two blade maxi on my 340 and love it. However, if you want a really smooth ride, by the 3 blade maxi. But considering you have a two cylinder engine, it might not be as much help as it would be on the a three cylinder unit. Cost = about 2 boat units for a 2 blade, 3 boat units for a 3 blade. See PYI for exact numbers. No I am not a dealer. Just a satisfied customer. Note, a boat unit is equal to $1,000. Jim
Have we tested the prop?
Tom & Wally: Our H'31 was over propped from the get go. We also have the same engine 2GM20F. Our boat came with a 15 x 12 prop. We were never able to get the max RPM's from the engine. We have a composite 15 x 10 prop and are still a little over. What you need to do is make sure that your engine governor is set properly (we also had this problem) and no other engine problem. You engine needs to be able to rev to 3600-4000 rpm's in netural (just rev it up and see if it will do it). Next you need to be able to get 3600 RPM in gear. You can do this at the dock (if they are strong enough) or try it in flat water. If you cannot get to the 3600 rpm target you are probably over propped. Assuming that the bottom is clean, prop clean etc. etc. then you need to get an experienced prop company to help you with your problem. If you are not getting the proper revs you can de-pitch your prop. If you are able to rev way past the 3600 RPM mark you may be under pitched. 1 degree of pitch is equal to about 250 rpms. Each inch of diameter also is worth about 250 rpms (these are estimates). If you are looking to keep a 2 bladed prop, you may want to contact Kilian Prop in San Leandro, CA. These guys do miracles with props.
Tom & Wally: Our H'31 was over propped from the get go. We also have the same engine 2GM20F. Our boat came with a 15 x 12 prop. We were never able to get the max RPM's from the engine. We have a composite 15 x 10 prop and are still a little over. What you need to do is make sure that your engine governor is set properly (we also had this problem) and no other engine problem. You engine needs to be able to rev to 3600-4000 rpm's in netural (just rev it up and see if it will do it). Next you need to be able to get 3600 RPM in gear. You can do this at the dock (if they are strong enough) or try it in flat water. If you cannot get to the 3600 rpm target you are probably over propped. Assuming that the bottom is clean, prop clean etc. etc. then you need to get an experienced prop company to help you with your problem. If you are not getting the proper revs you can de-pitch your prop. If you are able to rev way past the 3600 RPM mark you may be under pitched. 1 degree of pitch is equal to about 250 rpms. Each inch of diameter also is worth about 250 rpms (these are estimates). If you are looking to keep a 2 bladed prop, you may want to contact Kilian Prop in San Leandro, CA. These guys do miracles with props.
Tom
If buying a new prop you might check with Flex O Fold. He takes your boat spec's and sells you a prop for it. Made a Huge difference on my 45' Cost was $1320. Two blade folder. Not a dealer very Happy customer with money left to take wife to dinner!
If buying a new prop you might check with Flex O Fold. He takes your boat spec's and sells you a prop for it. Made a Huge difference on my 45' Cost was $1320. Two blade folder. Not a dealer very Happy customer with money left to take wife to dinner!
3600-4000 RPM?!?!?!
I thought cruising RPM was around 2800 on the Yanmar. If I push it into the 3200-3400 range I can surf this puppy. I thought that was WAY over-revved. Anyone know of a definitive source on this? Also, my throttle constantly slips down to about 2200 if I don't watch it.
I thought cruising RPM was around 2800 on the Yanmar. If I push it into the 3200-3400 range I can surf this puppy. I thought that was WAY over-revved. Anyone know of a definitive source on this? Also, my throttle constantly slips down to about 2200 if I don't watch it.
Tom don't over-rev.
Tom: You are correct that the cruising range on the engine is about 2800 rpm (actually 2500-3000 est). This number is 70%-80% of the MAX rating for your engine which is (3600rpms). The point being that a prop is similar to a rear end in a car. If you had a .456 in your hot rod car you would only have a top speed of maybe 90 mph if you have .320 gears you can go 140mph etc etc. The point being is that your engine should not rev much past 3600 rpms when in gear. If it does that means that there is not enough BITE from the prop (under-propped). On the other hand if you can only get 2800 rpms at wide open throttle (WOT) then you are over-propped.
Tom: You are correct that the cruising range on the engine is about 2800 rpm (actually 2500-3000 est). This number is 70%-80% of the MAX rating for your engine which is (3600rpms). The point being that a prop is similar to a rear end in a car. If you had a .456 in your hot rod car you would only have a top speed of maybe 90 mph if you have .320 gears you can go 140mph etc etc. The point being is that your engine should not rev much past 3600 rpms when in gear. If it does that means that there is not enough BITE from the prop (under-propped). On the other hand if you can only get 2800 rpms at wide open throttle (WOT) then you are over-propped.
Slipping throttle.
Tom: You also mentioned that the throttle cable was slipping. I posted an article in the Photo Forum regarding this subject. There is a "J" clamp that will help with this problem. Take a look and see if this helps you out.
Tom: You also mentioned that the throttle cable was slipping. I posted an article in the Photo Forum regarding this subject. There is a "J" clamp that will help with this problem. Take a look and see if this helps you out.
Thank you all - and one last question
I learned a lot from this thread and I appreciate your help. I'll follow your suggestions and let you know how it turns out. SHOULD I be able power along at hull speed?
I learned a lot from this thread and I appreciate your help. I'll follow your suggestions and let you know how it turns out. SHOULD I be able power along at hull speed?
3600 RPM ..... no problem
so I think it is propped okay. We got the motor where it is supposed to be in the engine compartment and it ran really smooth tied to the dock in forward up to 3600 rpm (a little bouncy at 1500). So I think mine is going to do a lot better now. As to the throttle creep, I have the j-clamp all the way down and the thottle still creeps back and holds steady at 2000. The mechanic said I should try to install it near the throttle in the pedestal. Guess its worth a try.
so I think it is propped okay. We got the motor where it is supposed to be in the engine compartment and it ran really smooth tied to the dock in forward up to 3600 rpm (a little bouncy at 1500). So I think mine is going to do a lot better now. As to the throttle creep, I have the j-clamp all the way down and the thottle still creeps back and holds steady at 2000. The mechanic said I should try to install it near the throttle in the pedestal. Guess its worth a try.
Wally "J"
Wally: The instructions on the "J" clamp state that it should be placed as close to the throttle handle as possible. I think this can be done on the newer pedestals. On our older units the engine compartment was about as close as we can get them. Maybe you do not have a Morse cable or it is a different model.
Wally: The instructions on the "J" clamp state that it should be placed as close to the throttle handle as possible. I think this can be done on the newer pedestals. On our older units the engine compartment was about as close as we can get them. Maybe you do not have a Morse cable or it is a different model.
Thanks Steve...
yep the factory or the dealer installed it next to the mount on the engine, so I will move it tomorrow. I was looking at access yesterday and it appears that I should be able to get a wrench on it through the top of the pedestal... w
yep the factory or the dealer installed it next to the mount on the engine, so I will move it tomorrow. I was looking at access yesterday and it appears that I should be able to get a wrench on it through the top of the pedestal... w
Tom...
I went out to the lake today to test my alignment and noticed that I can get about 4.2 knots at 2800 RPM. Full throttle is about 6 knots at 3500. I'm happy with the way it's running now in that I can cruise at 2800 or even 3500 for a short time without severe vibration. I also followed Steve's advice and relocated the J-clamp on the throttle cable near the throttle inside the pedestal and it works!!! Much less cable friction, smoother throttle operation, and no creeping back to 2000. So I think all of my motoring issues have been resolved (for now
Thanks all... w
I went out to the lake today to test my alignment and noticed that I can get about 4.2 knots at 2800 RPM. Full throttle is about 6 knots at 3500. I'm happy with the way it's running now in that I can cruise at 2800 or even 3500 for a short time without severe vibration. I also followed Steve's advice and relocated the J-clamp on the throttle cable near the throttle inside the pedestal and it works!!! Much less cable friction, smoother throttle operation, and no creeping back to 2000. So I think all of my motoring issues have been resolved (for now
Thanks all... wHull Speed...
Tom, I forgot to add that I think that mine is running as good as the current motor/prop combination will allow. Cruising at 4.2 is short of hull speed tho, but then I'm not confident that a different prop would give us 2+ more knots at cruising RPM. I tend to think that it's merely a HP/displacement and/or engine performance limitation. I had the same engine in a 4,000 pound lighter beneteau 281 and it would not motor at hull speed either and on that boat I had a 3-blade prop. What chaps me is that a buddy of mine has a 94 catalina 320 and it really moves. He claims that it'll do 9 knots at full throttle!!! All I know is that you can ski behind it...lol. He has 3 cylinder engine that has another 9 Hp but the boat weighs a ton+ more than ours. What's up with that? Purely engine performance I guess but motoring next to him gives me an inferiority complex. If there is a prop maker that would guarantee another 2 knots cruising speed than I would order one tomorrow. later w
Tom, I forgot to add that I think that mine is running as good as the current motor/prop combination will allow. Cruising at 4.2 is short of hull speed tho, but then I'm not confident that a different prop would give us 2+ more knots at cruising RPM. I tend to think that it's merely a HP/displacement and/or engine performance limitation. I had the same engine in a 4,000 pound lighter beneteau 281 and it would not motor at hull speed either and on that boat I had a 3-blade prop. What chaps me is that a buddy of mine has a 94 catalina 320 and it really moves. He claims that it'll do 9 knots at full throttle!!! All I know is that you can ski behind it...lol. He has 3 cylinder engine that has another 9 Hp but the boat weighs a ton+ more than ours. What's up with that? Purely engine performance I guess but motoring next to him gives me an inferiority complex. If there is a prop maker that would guarantee another 2 knots cruising speed than I would order one tomorrow. later w
Wally/Tom Tom/Wally
Hey you guys never mentioned how you were determining your speed. Where you using the knot meter or a GPS. If you are using a knot meter, do you know if it is calibrated correctly? If you are using both I suppose that you know that they should be close. Both of you are in protected waters and I would assume that there is very little current if any! GPS is reading SOG (speed over ground) and the knot meter is SOW (speed over water). I would think that both of these boats should reach something very close to hull speed without over-reving (2800-3000rpms). I'd check this with my dealer and the factory for their take on this.
Hey you guys never mentioned how you were determining your speed. Where you using the knot meter or a GPS. If you are using a knot meter, do you know if it is calibrated correctly? If you are using both I suppose that you know that they should be close. Both of you are in protected waters and I would assume that there is very little current if any! GPS is reading SOG (speed over ground) and the knot meter is SOW (speed over water). I would think that both of these boats should reach something very close to hull speed without over-reving (2800-3000rpms). I'd check this with my dealer and the factory for their take on this.
Smooth water test
I tried over-revving the engine and had no vibrations all the way up to 3600 so I assume the alignment and prop are fine. My knotmeter is worthless (has an error in the 1.5 knot range on port tack and .3 knot on starboard - yes I've calibrated it) but two GPS's show the boat moving at 5.9 kts in glassy water. I think the mismatch might just be expectations vs reality! Thanks of rall the info
I tried over-revving the engine and had no vibrations all the way up to 3600 so I assume the alignment and prop are fine. My knotmeter is worthless (has an error in the 1.5 knot range on port tack and .3 knot on starboard - yes I've calibrated it) but two GPS's show the boat moving at 5.9 kts in glassy water. I think the mismatch might just be expectations vs reality! Thanks of rall the info
Steve...
I am only reporting what my knot meter says as I don't have GPS yet. What I reported was under smooth water and no wind conditions. It is possible that my knot meter is not accurate in that it has not been calibrated to my knowledge. So I will do that when I get a GPS. Thanks again Steve, you have been a great help. If you ever get to Austin let me know. w
I am only reporting what my knot meter says as I don't have GPS yet. What I reported was under smooth water and no wind conditions. It is possible that my knot meter is not accurate in that it has not been calibrated to my knowledge. So I will do that when I get a GPS. Thanks again Steve, you have been a great help. If you ever get to Austin let me know. w
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