I read a thread, in which a B361 owner mentions 6.5 kts under power, he does not mention rpm. My 2003 model with a Westerbeak and fixed 3 blade prop will not reach 6 kts until well over 3000 rpm! With a freshly painted bottom, in flat water she will do 5.0 kts. at 2000rpm. I need to run at 2700 rpm to get 5.5kts. I have suspected the prop has the wrong pitch. Any feed-back would be appreciated. Also, has anyone seen an appreciable increase in speed under power after adding a feathering prop?
B361 slow under power
- Thread starter Tarsie
- Start date
- Status
We had a 2002 361 with the Westerbeke 30B and cruised under power at 7kts. Can't remember the RPMs but it was apx 80% of max. We had an Autoprop on her which may have made a difference but not as much as you mention. It was installed when the boat was delivered so I can't give you before and after references. Good luck.
If you run the engine up to it's max rpm in neutral, you should be able to get close to that same rpm when motoring. If not, you need to lessen the pitch of your prop. If, in gear, you can not get close to that max rpm, you are loading the engine and not doing it any good. Let a prop shop or manufacturer calculate your needs, both for what you presently have, and for any change in pitch needed. I did just that, and with fresh paint on the bottom, the boat thru the water was like a hot knife cutting butter. I have a Gori folding 2-blade on my B323 3YM20.
How are you measuring speed? Maybe your knotmeter is not correct.
If GPS is used what about current.
Other than that sounds like you might be underpitched. Any smoke at max RPM?
The feathering prop is mainly to improve sailing performance, although backing is said to get better as well.
If GPS is used what about current.
Other than that sounds like you might be underpitched. Any smoke at max RPM?
The feathering prop is mainly to improve sailing performance, although backing is said to get better as well.
Hello Guys,
Thanks for the replys; to answer the questions asked: I am able to run up to 3600 rpm in neutral and about the same in forward without any smoke, the engine runs great. I will admit that I am a bit afraid to hold at this high an rpm long enough to find the speed over ground, but have done the test. I operate between 2000 and 2600 rpm normally and have never seen close to 6 kts. What do others use for cruising rpm? I do not use the knot meter to view speed, always the gps SOG.
No, you cannot use SOG to check your speed because this is always affected by currents etc. Choose a calm day with no wind and use speed on the water instead and make sure that little propeller measuring the speed is clean and runs freely.
Now, for some measurements:
I have a Beneteau Oceanis 361 with Volvo Penta MD2030 (29hp) and a 2-blade fixed propeller size 16X11.
I can achieve up to 3400rpm maximum and cruise at 2400-2600 (usually 2400). On a calm day with a clean hull and clean propeller I can achieve a speed on the water of 6.2-6.3 at 2400rpm and 5.0-5.1 knots at 2000rpm.
Please note that these speeds can be achieved only with a really clean propeller. After my summer trip, I couldn't use my boat for 3 weeks due to some maintenance (a change of the forestay). As soon as I used it again I could achieve only up to 5.8 at 2400rpm (0.5 knot less!). After cleaning the propeller again during anchorage (though didn't look that dirty) I could see again the same speed of 6.2-6.3 at 2400rpm.
Philip, thanks for your reply. Interesting that you can get an additional 1.2 kts winth 400 more rpm, was the two blade prop original, from the factory? I have checked the speed numerous times over the past 3.5 years, always with the same result.
Joe, We have Mike B's old 361 with the folding prop. Really enjoy the prop, easily get the performance Mike describes. I'm like you, I rarely run at max, usually 2600rpm.
Bob
Bob
My 2002 B361 will cruise at 7 kts (verified by GPS) with a new bottom (VC17) at 2800 (Yanmar 3Gf) with maxprop. A little slime slows her to 6kts as the season progresses. Bottom condition is a HUGE factor.
Agaliha
Agaliha
According to Beneteau (in France) the propeller is "PN 517060, 2-blade 16X11 RH25 K11" and yes, it is the original.
Attached is a photo.
Attachments
I have a 373. It came with 3 blade 12x18 3 bladed prorp and 3JH4E 39 hp. Max rpm was 3100 at 8.1 knots. I changed to a feathering Kiwiprop 3 blade and did 7+ max. I increased the pitch 3/4 turns and lost 300 rpm and maxed out to 6.8 knots. I am over pitched since I can not attain the 3100. I will turn it back 3/4 turns this spring. I will live with the lower top speed under power to gain 3/4 knot sailing speed and better rudder control i.e., half the weather helm angle.
The 361 in the marina has a 3 bladed prop that appears the same size as my fixed prop. I do not know his engine size.
The 361 in the marina has a 3 bladed prop that appears the same size as my fixed prop. I do not know his engine size.
Attachments
Does anyone out there have any experience with a Varifold prop on a Beneteau.
I am considering the feathering version for my B331.
I am considering the feathering version for my B331.
- Status