Vovo Recommended RPMs when full power needed over long time

[BarbofCapeCod]

I am new CD-28 owner. My boat, Celtic Ray, has a Volvo MD2B engine. The other day we had to make headway directly into a 25 kt head wind, gusting to 35 kt, among the numerous shoals of Nantucket Sound that required us to motor. The seas were such that the boat was stopped on several occasions after hitting steep waves, resulting from a 2-4 kt current going to windward. By increasing the RPMs to 2200 we were able to make steady progress over a long seeming, 6 hour passage.

My question is: what would you recommended as the maximum cruising RPM for this motor over a several hour period?

Also, does anyone have a prop recommendation?

In addition, we used the roller furling head sail, with about three feet on the stay, to stabilize her. Do you have any suggestions about sail configuration when motoring to windward in a nasty chop?

Sincerely,
Bill White

[Stan W.]

of publications on motors no longer in production. It appears max RPM for the MD2B is 2500 so 2200 should be fine. Diesels like to be worked hard. Basically, as long as it's not overheating or billowing clouds of dark smoke, all is well.

A three-bladed prop would be much better in those conditions but it would hurt sailing performance and feathering props are big bucks and add another thing that can go wrong.

I prefer to motorsail with a reefed main instead of a mostly furled genny. You can steer closer to the wind that way, especially if you have a traveler and pull it to windward. Either way, you have to be careful not to heel too much when the motor is running or it may starve for lube oil. The rule of thumb I've heard is no more than 20 degrees, but even that seems like a lot to me.

[BarbofCapeCod]

Thank you for the reply. I'll look for the manual (again) on the Volvo site.

[Wayne Grenier]

I am not sure I'd want to buck 25-35 knt headwinds in Nantucket sound for 6 hours! as a matter of fact-now that I think about it-I'd rather stay home-! I did go down Vineyard Sound last year with a 20-25 knt tail wind-but my hat is off to you! ( I really don't like Nantucket that much anyway)

[Larry DeMers]

I have this engine in our CD30, and the manual says 2600rpm is top, although, my installation will go to 2800 with the current prop (original 2 blade fixed), which seems to be slightly underpitched, given the max rpm I can reach.

The power band for this engine is 2000-2500 rpm, so you are right in the midst of the range, and should be fine.

I once spent 3 hours in front of Bayfield, WI., trying to get home in a 40-50kt. fall snow storm. So I know how frustrating this can be. One trick I have used in higher winds like this, is to "sail" the boats hull while motoring. If you take a course that is about 45 degrees to the wind/waves, your SOG will double easily. Make short tacks about every 5-10 min. and you will get home a lot faster. The idea is to use the shape of the hull as a 'sail'. It works! Don't laugh.

Cheers,

Larry DeMers
s/v DeLaMer
CD30c Lake Superior