My Yanmar 27 hp seems to be underpowered. I cannot reach hull speed with engine at 3400 RPM in calm waters. The engine has the standard two bladed prop that Hunter installs at the factor. Has anyone else had this problem? What did you do to get better performance?
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Get a three bladed prop
It's up to you, but the two-bladed prop is just minimum equipment in my opinion. When we bought our 356, the dealer recommended a three-bladed prop because it provides more power, and is relatively inexpensive in boat bucks. They were right. We use 2800rpm as usual cruise and get about 6.5 kts through the water. Also, going out on a limb here, I don't think anyone will recommend 3400 rpm as a normal operating speed- if that's what you are using 3400 for - (unless they are a diesel mechanic who needs work). With the three-bladed prop, I'd recommending using about 2800 as a normal cruise.
It's up to you, but the two-bladed prop is just minimum equipment in my opinion. When we bought our 356, the dealer recommended a three-bladed prop because it provides more power, and is relatively inexpensive in boat bucks. They were right. We use 2800rpm as usual cruise and get about 6.5 kts through the water. Also, going out on a limb here, I don't think anyone will recommend 3400 rpm as a normal operating speed- if that's what you are using 3400 for - (unless they are a diesel mechanic who needs work). With the three-bladed prop, I'd recommending using about 2800 as a normal cruise.
Red Herring
I have researched this issue. The 356 is not underpowered. The three bladed prop will buy you slightly less rpm for the same boat speed, though principally at low speeds, but its biggest advantage is smoothness and lack of vibration, not thrust. I had low boat speed with high engine rpm also, but found out that the biggest problem was not the prop, as I had initially thought, but that my speed gauge (Raymarine ST-60) was not properly calibrated and was reading way too low. The dealer was supposed to do the calibration but did not. The instructions are in the instrument manual and they are simple, to be done by the owner. Once I did a measured course calibration the indicated speed at 3000 rpm went up from 5.6 knots to 6.4 knots. And at 3400 I get about 7 knots. The problem was not an underpowered engine or wrong prop, but an uncalibrated speedometer. There are two other possible causes of your problem: Dirty bottom or dirty prop (they must be kept clean of growth for top speed, though if your engine reaches 3400 rpm I would suspect growth on the bottom more than on the prop), and possibly the wrong diameter/pitch on the prop (though if it came from Hunter I would doubt it). By the way, the best Yanmar expert on the East Coast, an ex-nuclear sub chief who heads the shop at at Norton's and really knows his business and teaches a Yanmar class, told us that the Yanmar in the 356 can run all day under load at 3400 rpm and will have a life greater than 10,000 hours, and at 3200 will last over 100,000 hours. But at 3600 rpm it has a very short life--the falloff curve is very steep. So don't be afraid to run at 3200-3400 rpm. But the main point is that there should be no need to run the engine that fast to get over 6 knots speed. In summary I recommend switching to the 15x13 three blade prop, but only AFTER you have calibrated the speedometer and cleaned the prop and bottom, as that will probably solve your problem. So don't be afraid to run at 3200-3400 rpm all day under load, though you should not have to do that to get 6.5 knots. If you want to discuss further contact me at ibekey@aol.com Ivan Bekey H356 #157
I have researched this issue. The 356 is not underpowered. The three bladed prop will buy you slightly less rpm for the same boat speed, though principally at low speeds, but its biggest advantage is smoothness and lack of vibration, not thrust. I had low boat speed with high engine rpm also, but found out that the biggest problem was not the prop, as I had initially thought, but that my speed gauge (Raymarine ST-60) was not properly calibrated and was reading way too low. The dealer was supposed to do the calibration but did not. The instructions are in the instrument manual and they are simple, to be done by the owner. Once I did a measured course calibration the indicated speed at 3000 rpm went up from 5.6 knots to 6.4 knots. And at 3400 I get about 7 knots. The problem was not an underpowered engine or wrong prop, but an uncalibrated speedometer. There are two other possible causes of your problem: Dirty bottom or dirty prop (they must be kept clean of growth for top speed, though if your engine reaches 3400 rpm I would suspect growth on the bottom more than on the prop), and possibly the wrong diameter/pitch on the prop (though if it came from Hunter I would doubt it). By the way, the best Yanmar expert on the East Coast, an ex-nuclear sub chief who heads the shop at at Norton's and really knows his business and teaches a Yanmar class, told us that the Yanmar in the 356 can run all day under load at 3400 rpm and will have a life greater than 10,000 hours, and at 3200 will last over 100,000 hours. But at 3600 rpm it has a very short life--the falloff curve is very steep. So don't be afraid to run at 3200-3400 rpm. But the main point is that there should be no need to run the engine that fast to get over 6 knots speed. In summary I recommend switching to the 15x13 three blade prop, but only AFTER you have calibrated the speedometer and cleaned the prop and bottom, as that will probably solve your problem. So don't be afraid to run at 3200-3400 rpm all day under load, though you should not have to do that to get 6.5 knots. If you want to discuss further contact me at ibekey@aol.com Ivan Bekey H356 #157
Ditto the three blade
We have a three blade on our 356. According to my GPS, we can do around 7.5 kts at 2800 - 3000 rpm. The three blade has a lot more dig than the two blde we had on our previous 290.
We have a three blade on our 356. According to my GPS, we can do around 7.5 kts at 2800 - 3000 rpm. The three blade has a lot more dig than the two blde we had on our previous 290.
Agree with Darcy & Ivan
I'm getting same speeds as Darcy with a three blade prop and 2800 rpm. Jim S/V Java
I'm getting same speeds as Darcy with a three blade prop and 2800 rpm. Jim S/V Java
Hull Speed
Folks - The point Ivan made is very valid. Calibration of the knotmeter whether by measured course or by GPS is the essential first step. If my calculations are right, the theoretical hull speed on a 356 is 7.41 kts. Using the formula of 1.34 x sq.rt. LWL, I get 1.34 x 5.53 = 7.41. I would consult with a dealer or Yanmar as to what rpm will get you to hull speed. IMHO, if that is 3,000 rpm, then there would be few reasons to exceed that under the same conditions. Obviously, running against a current or tide may require higher rpm to deliver an equivalent speed. But the bottom line, I think, is to get the measuring instruments calibrated so that you are working with valid data. Fair winds, Steve S/V Options H380
Folks - The point Ivan made is very valid. Calibration of the knotmeter whether by measured course or by GPS is the essential first step. If my calculations are right, the theoretical hull speed on a 356 is 7.41 kts. Using the formula of 1.34 x sq.rt. LWL, I get 1.34 x 5.53 = 7.41. I would consult with a dealer or Yanmar as to what rpm will get you to hull speed. IMHO, if that is 3,000 rpm, then there would be few reasons to exceed that under the same conditions. Obviously, running against a current or tide may require higher rpm to deliver an equivalent speed. But the bottom line, I think, is to get the measuring instruments calibrated so that you are working with valid data. Fair winds, Steve S/V Options H380
Try repitching the prop
I can only speak from my experience, but the pitch of the prop is very critical. I have had a Vision 32 for 13 years, and am on my second prop (the first eaten by galvanic corrosion). The Vision also has a Yanmar 3GM30. My first prop would propel the boat at 7 knots at 2800 rpm. The replacement prop would only hit about 6 knots, and was very effected by headwinds. I had the prop repitched, and now the boat performs as before. At 3400 rpm, I can hit about 7.5 knots, really pushing the hull speed. I've verified these numbers by GPS on numerous occasions. In any case, the 3GM30 has plenty of power to spare for my boat when its connected to the proper prop. I don't doubt the claims of those with 3-blade props, but IMHO really don't think its necessary, given the reduction in speed under sail. I'm very happy with my 2-blade. Go to a good propeller shop, explain your problem, and give them a shot at it. I think you'll be suprised at the results.
I can only speak from my experience, but the pitch of the prop is very critical. I have had a Vision 32 for 13 years, and am on my second prop (the first eaten by galvanic corrosion). The Vision also has a Yanmar 3GM30. My first prop would propel the boat at 7 knots at 2800 rpm. The replacement prop would only hit about 6 knots, and was very effected by headwinds. I had the prop repitched, and now the boat performs as before. At 3400 rpm, I can hit about 7.5 knots, really pushing the hull speed. I've verified these numbers by GPS on numerous occasions. In any case, the 3GM30 has plenty of power to spare for my boat when its connected to the proper prop. I don't doubt the claims of those with 3-blade props, but IMHO really don't think its necessary, given the reduction in speed under sail. I'm very happy with my 2-blade. Go to a good propeller shop, explain your problem, and give them a shot at it. I think you'll be suprised at the results.
Replaced my 2 blader last year
I must agree with Ivan as I replaced my 2 blade with a 3 blade sailor style and it was like I put a new motor in the boat. No more vibration, rattling, or waiting for ever to stop. This is with a motor that needed new motor mounts and a cutlass bearing totaly gone. "Both replaced over the winter" The prop did have to high a pitch thou as I was only getting 2900 rpm's at WOT. The pitch was 13" lowered it to 11" this should put me at 3400 rpms in flat water conditions. I go in this Tuesday and can't wait..
I must agree with Ivan as I replaced my 2 blade with a 3 blade sailor style and it was like I put a new motor in the boat. No more vibration, rattling, or waiting for ever to stop. This is with a motor that needed new motor mounts and a cutlass bearing totaly gone. "Both replaced over the winter" The prop did have to high a pitch thou as I was only getting 2900 rpm's at WOT. The pitch was 13" lowered it to 11" this should put me at 3400 rpms in flat water conditions. I go in this Tuesday and can't wait..
Yo Ivan!
When you say Norton's, do you mean Norton's in Deltaville? Steve Price shop closed up last year, if that's whom you're referring to. If not, who? Thanks.
When you say Norton's, do you mean Norton's in Deltaville? Steve Price shop closed up last year, if that's whom you're referring to. If not, who? Thanks.
CHeck knot meter
BE sure and verify true boat speed. I see you're from Olympia (Washington?). Finding slack water up there is not easy. But when you do verify speed with your GPS. Also check the "wheel" on your hull knot meter to make sure its spinning freely. Bob F. "Andiamo"
BE sure and verify true boat speed. I see you're from Olympia (Washington?). Finding slack water up there is not easy. But when you do verify speed with your GPS. Also check the "wheel" on your hull knot meter to make sure its spinning freely. Bob F. "Andiamo"
craig at norton's
craig the service manager at norton's he's the best yanmar expert ivan was talking about.
craig the service manager at norton's he's the best yanmar expert ivan was talking about.
The first Hunter 356 introduced in England
An article in the British magazine "Yachting Monthly" dated March 2002 in which the first Hunter 356 (known in England as the Legend 356) was tested exhibited the exact same symptoms slow speed at what should be "normal" cruising RPM. Only at super-high revs did they approach acceptable speed. That boat, like yours, had the two bladed prop. The three bladed prop may be the solution, or a two bladed prop whith a much higher "pitch." Unless you are a die-hard racer the three blade is better anyway for most uses. Charles Frick, Boca Raton Fl
An article in the British magazine "Yachting Monthly" dated March 2002 in which the first Hunter 356 (known in England as the Legend 356) was tested exhibited the exact same symptoms slow speed at what should be "normal" cruising RPM. Only at super-high revs did they approach acceptable speed. That boat, like yours, had the two bladed prop. The three bladed prop may be the solution, or a two bladed prop whith a much higher "pitch." Unless you are a die-hard racer the three blade is better anyway for most uses. Charles Frick, Boca Raton Fl
Speed?
We have no complaints after a season with our 356 with a two blade prop. If I wanted more speed I'd have bought a power boat!
We have no complaints after a season with our 356 with a two blade prop. If I wanted more speed I'd have bought a power boat!
scotts right
i do use my motor- rarely. i have used 55 gallons of diesel in 4 years which includes the 90 miles of motoring we had to do to move the boat upon delivery due to no wind. i hate the smell of diesel, and, if the winds not blowing or supposed to blow, i don't go. i have a 1989 model that has 760 hrs. on the saildrive, so apparently her previous owner felt the same way.
i do use my motor- rarely. i have used 55 gallons of diesel in 4 years which includes the 90 miles of motoring we had to do to move the boat upon delivery due to no wind. i hate the smell of diesel, and, if the winds not blowing or supposed to blow, i don't go. i have a 1989 model that has 760 hrs. on the saildrive, so apparently her previous owner felt the same way.
Agree with Ivan!
My st-60 was also not calibrated, and was reading 2 knots low-based on reciprocal runs in no current- with the 3 blade 15x13 from Hunter I was getting just under 7.5 kts @3400. that prop was eaten (a long story!) and Hunter replaced it with the newer 16x11 3 blade, first day out we had comparable speed, certainly fast enough! the 3 blade gives you more smoothness and control, especially when backing
My st-60 was also not calibrated, and was reading 2 knots low-based on reciprocal runs in no current- with the 3 blade 15x13 from Hunter I was getting just under 7.5 kts @3400. that prop was eaten (a long story!) and Hunter replaced it with the newer 16x11 3 blade, first day out we had comparable speed, certainly fast enough! the 3 blade gives you more smoothness and control, especially when backing
Raymarine ST60 Speed matches GPS
Red, Thanks so much for the info. The boat is less than three months old and I just had the bottom checked by a diver who said it is in great shape. I will have a diver scrub the bottom, check the zincs and clean the thru-hulls every three to four months. I think that is a small price to pay to protect this investment. Also, I have checked the ST-60 against my Garmin 182C chart plotter in calm waters. Most of the time they match exactly or may vary a tenth of a knot or so. So, I don't think the instrument calibration is the issue. The only time I have ever reached hull speed is when I was running at about 3000 rpm with a flood or ebb tide in fairly strong current. Perhaps a prop change, as you suggest, will improve the situation. Thanks again for you comments. John
Red, Thanks so much for the info. The boat is less than three months old and I just had the bottom checked by a diver who said it is in great shape. I will have a diver scrub the bottom, check the zincs and clean the thru-hulls every three to four months. I think that is a small price to pay to protect this investment. Also, I have checked the ST-60 against my Garmin 182C chart plotter in calm waters. Most of the time they match exactly or may vary a tenth of a knot or so. So, I don't think the instrument calibration is the issue. The only time I have ever reached hull speed is when I was running at about 3000 rpm with a flood or ebb tide in fairly strong current. Perhaps a prop change, as you suggest, will improve the situation. Thanks again for you comments. John
Speed is not the issue
Scott, I'm with you - the issue is not so much about speed as it is about performance. I just paid a sizable hunk of change for a piece of equipment that is supposed to perform to a certain advertised standard and it doesn't seem to be doing that. To my recollection, in three years of sailing (had a MacGregor before my Hunter)I can't ever recall motoring when I could sail, unless it was to get through the channel to my slip. Perhaps you are fortunate enough to have winds everyday in VA. Here on the South Puget Sound, the winds are vary sporadic during the summer months which means you will have to motor if you are going to use your boat. In the winter, it is another story - we often have more wind than is comfortable. At this time of the year, the winds are pretty good. In the Straits of Juan de Fuca last Saturday several boats were demasted in a boat race in winds over 45 knots. In winds like that, you probably should be motoring, but with just 6.5 knots of boat speed in still waters at 3200-3400 RPM, you might find it quite challenging to motor against the tide and/or winds. You may even find yourself going backwards - and, I don't mean in reverse either. Enjoy your sailing
Scott, I'm with you - the issue is not so much about speed as it is about performance. I just paid a sizable hunk of change for a piece of equipment that is supposed to perform to a certain advertised standard and it doesn't seem to be doing that. To my recollection, in three years of sailing (had a MacGregor before my Hunter)I can't ever recall motoring when I could sail, unless it was to get through the channel to my slip. Perhaps you are fortunate enough to have winds everyday in VA. Here on the South Puget Sound, the winds are vary sporadic during the summer months which means you will have to motor if you are going to use your boat. In the winter, it is another story - we often have more wind than is comfortable. At this time of the year, the winds are pretty good. In the Straits of Juan de Fuca last Saturday several boats were demasted in a boat race in winds over 45 knots. In winds like that, you probably should be motoring, but with just 6.5 knots of boat speed in still waters at 3200-3400 RPM, you might find it quite challenging to motor against the tide and/or winds. You may even find yourself going backwards - and, I don't mean in reverse either. Enjoy your sailing
Keep your RPM down
Just because a motor CAN do something, doesn';t mean it SHOULD do that thing! Keep in mind the motor is there as an auxiliary source of locomotion, for harbor navigation, docking, and the like. Running her at 3200 ROM is overkill, except in extremem situstions. I prefer to give up speed( which is dangerous in the harbor) for a lower RPM. It saves wear and tear on the engine which saves boat dollars down the line. Good luck
Just because a motor CAN do something, doesn';t mean it SHOULD do that thing! Keep in mind the motor is there as an auxiliary source of locomotion, for harbor navigation, docking, and the like. Running her at 3200 ROM is overkill, except in extremem situstions. I prefer to give up speed( which is dangerous in the harbor) for a lower RPM. It saves wear and tear on the engine which saves boat dollars down the line. Good luck
356 speed
Mark's got the right idea! On the 356 you need to watch the stern under power-as you increase the rpms, the stern settles-once the rubrail hits the water, you won't go any faster, you'll just burn more fuel!
Mark's got the right idea! On the 356 you need to watch the stern under power-as you increase the rpms, the stern settles-once the rubrail hits the water, you won't go any faster, you'll just burn more fuel!
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