• Mobile App For Android Now Online!

    Download it here. The app is searchable in the Google Play Store under Sailboat Owners.

    Sorry iPhone/iPad users, we are still waiting on Apple. :(

    Click the X in the upper right corner to make this go away

Seems Under Power Slow - Hunter 34

Jan 13, 2015
60
Hunter 34 Deep Bay, BC
My Hunter 34 six-months-new-to-me only makes about 4 knots under power at 2600 rpm. That seems awfully slow to me. I was told by the PO that he put a fixed-blade prop on it that was not quite right for the boat, and I'm inclined to agree. What is the correct spec for the prop on this boat, and what speed should I expect under power? Opinions on folding versus fixed, three blade versus two?

The 3GMF Yanmar is rated for 3,000 or 3,600 rpm in the manual (depending on which test they use). What is the recommended cruising rpm for long distance?

Thanks in advance.
 
Jan 13, 2015
60
Hunter 34 Deep Bay, BC
Bit of further information: the prop walk in reverse seems extreme to me. At moderate throttle (say, 1,500 rpm) from a dead stop, the stern swings strongly to port even with the wheel hard over to starboard as she starts back. Even with some way on in reverse, the stern keeps swinging to port. I can only straighten her out if I drop back to idle or just over.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
I think that you need to go to a good prop shop and give them your specs. As I remember this model takes a 15" blade. The pitch will be determined by the number of blades. If you have that much prop walk the prop may be oversized causing the excess walk.

The normal crushing rpm is about 2500-3000 with the correct prop.
 
Feb 8, 2014
1,239
Columbia 36 Muskegon
Did you mean you can only reach 2600 rpm at wide open throttle? Assuming the tach is reading correctly (which they often do not), you should be able to hit 3000 with a clean prop and bottom, and cruise at 2800. It does sound like you're over propped, and that would also explain the excessive prop walk. Are you getting any black smoke at WOT? That's another symptom. One of the first things to check is actual rpm. If you can rent or borrow an optical tach you can verify that your installed tach is correct, then base your further actions on that.
 
Jun 3, 2004
886
Hunter 34 Toronto, Ontario Canada
The original prop on my '83 was a 2 blade 15X12. I could hit just under 7 knots at near to 3000 - reading from the tach and speed from a gps. I changed to a 3 blade Campbell sailor - 14X9 and now I get just under 7 at about 2500.
 

YVRguy

.
Jan 10, 2013
418
Hunter 34 Vancouver, BC
I think that you need to go to a good prop shop and give them your specs. As I remember this model takes a 15" blade. The pitch will be determined by the number of blades. If you have that much prop walk the prop may be oversized causing the excess walk.

The normal crushing rpm is about 2500-3000 with the correct prop.
I agree. 2600rpm is low. I have a 3GM with a 2 blade prop and I cruise at about 2900 rpm. Speed is between 5 - 6kts. Are you topping out at close to 2600 or are you just being super careful?
 
Jan 22, 2008
1,541
Hunter 34 Alameda CA
My original prop is still a 15 x 15 two blade. I run all the time at 3000 and with everything clean run right around 7.0 kts. This is with the Yanmar motor.

Prop walk is something managed. Leaving the engine engaged at a constant rpm results in significant prop walk. Applying a short burst of power then back to neutral allows one to drive the boat in a straight line at slower speed. Continuing to apply short bursts until more speed is achieved (making way) will eventually allow the rudder to bite and more directional control is had. I like the prop walk mine has. I can turn the boat completely around on its keel without using the wheel. Bring the boat to a complete forward stop. Lock it all the way to starboard. Apply a short high rpm burst in forward and back to neutral. as the stern starts to kick around do the same thing in reverse and it will continue to walk in a circle. Great for turning around in the wrong fairway.
 
Last edited:
Dec 14, 2003
1,208
Hunter 34 Lake of Two Mountains, QC, Can
Yanmar 3GM30F. I run a 15 X 11 RH 3-blade fixed prop and cruise at 6.5 knots (GPS) at 2650 RPM (flat water). In gear, WOT will bring her up to 3200 RPM and speed at 7.1. My tach is low by 50 RPM at 2650 and about 75 RPM at WOT when compared with an electronic tack pointed at the main pulley.
 
Nov 6, 2006
8,872
Hunter 34 Mandeville Louisiana
The original on my '85 was a Michigan Wheel "Sailor" at 15X15 . It had very narrow blades. I slung a blade in '08 and replaced with the same name prop but it has much wider blades and I am a little over-propped at 15X15 with this wider two blade. Gear ratio is 2.61:1 in forward
 
Jan 13, 2015
60
Hunter 34 Deep Bay, BC
Thanks for all the feedback. 2600 rpm is just where the PO told me he cruised. I have never tried WOT since growing up with gas inboard/outboards you never ran that way as the engines aren't designed for it. I'll give it a shot and see what rpm she'll reach. I'll also look into getting my hands on a strobe tach to confirm the real rpm, but the comments are pretty convincing that the prop is wrong. By the way, the hull is pretty clean; there is a little slime, but no barnacles or anything like that. You can see about 50% blue through the goo.

Are there any strong feelings on two-blade versus three?
 
Jan 22, 2008
1,541
Hunter 34 Alameda CA
Thanks for all the feedback. 2600 rpm is just where the PO told me he cruised. I have never tried WOT since growing up with gas inboard/outboards you never ran that way as the engines aren't designed for it. I'll give it a shot and see what rpm she'll reach. I'll also look into getting my hands on a strobe tach to confirm the real rpm, but the comments are pretty convincing that the prop is wrong. By the way, the hull is pretty clean; there is a little slime, but no barnacles or anything like that. You can see about 50% blue through the goo.

Are there any strong feelings on two-blade versus three?
3000 rpm is 80% of WOT. That is a typical recommended set point for these engines based on the perfomance curves.

Two blade versus Three... I'll not go there.
 

VINN

.
Aug 23, 2005
84
HUNTER H34 point lookout long island
I can offer more prop data for h34 owners. ive gone through so many experiments over the years it may help someone out there. my 84 came with a 15x12 and it did 3600 rpm at roughly 7 knots but was very weak driving into a headwind. some time a 50% loss in speed. lost a blade on that prop and changed to a 15x13. results were better. 3450 wot with better performance into a medium sea. than I went to a flexofold which over propped me badly at only 2850 wot. they recommended a 16.5x12. ive had it trimmed to a 15.5x12 with my own money, and its just about right spinning at 3050 wot and has good power punching through a 25 knot sea. when speed limited 2000 rpm is really smooth with the stern is still slightly above the wake at 5 knots+-. Cruz is ok around 2700 rpm at 6+ knots but louder an rougher. the only thing better is probably a 3 blade folding prop pitched correctly, for a smoother ride for a long haul point to point. then again its probably twice the money...maybe next summer
 
Jan 13, 2015
60
Hunter 34 Deep Bay, BC
Update: based on everyone's feedback, I took it out today and at WOT I only get to 3,100 rpm and approximately 5.5 knots. It seems to comfortably do 5 knots at 2,900, which is where I plan to run it until I can get the prop replaced with something more appropriate. There is no smoke at WOT.

It is a little difficult to get an accurate speed around here because there are strong tidal currents. To really get it accurate you need to make a run within a short period of time in the middle of a tide run in opposite directions, and average the GPS speed.

I plan to beg, borrow, or if absolutely necessary, buy, a strobe tach to confirm how close the onboard tach is to real life.

Thanks again for all the help.