Yankee 30 Message Board
Yankee 30 Message Board
Posted by Steve Botts on 12/26/2003, 9:47 am, in reply to "Y30 Prop?!?" --Previous Message-- With the reduction gear, at 3,600 RPM your shaft speed is about 1,300 RPM, so you need more pitch than I do, and maybe the third blade. Extending the shaft with a strut would get you cleaner water and give you more clearance to the hull, perhaps even allow a larger diameter prop, if the engine has enough power to turn it. You might check with some of the prop manufacturers to see what they would recommend. -Steve
68.122.225.68
: Hi Yankee sailors:
: I purchased hull 62 with a sick Atomic in May
: 2002. A couple of days ago,after struggles
: that nearly broke the back of my enthusiasm,
: I got the boat back in the water with a
: little 10hp Kubota marinized diesel in place.
: My installation is a copy of Bill Ramelli's
: on Andiamo, using a CV flexible joint and a
: glassed in thrust bearing plate. This has
: allowed me to mount the engine skewed to the
: prop shaft and fitting nicely in the
: existing space under the settee without any
: modifications, except the engine bed, in that
: area.
: My small diesel runs at 3600rpm max and has a
: 2.72:1 gear ratio in forward and 2.1:1 ratio
: in reverse. I am using a borrowed 12x12
: three-bladed prop as a trial horse, which I
: have allowed to stick out 3 inches behind the
: cutlass bearing in the keel in order to
: achieve some kind of clearance between the
: blades and the hull above. Even so this
: clearance is only about one inch which is
: certainly less than the stated minimum of 15%
: of prop diameter all propeller instructions
: mention.
: I have taken a couple of test trips and I am
: not happy with the propulsion. In forward
: the engine is able to reach max revs but the
: prop does not seem to have any real bite and
: starts singing (cavitating?) when I crank up
: hard. In reverse, with clearer water to grip
: and a smaller gear ratio the engine smokes
: and is not able to rev up.
: Obviously I must do something to pitch and
: diameter to improve the situation. I realize
: that a lot would be gained by extending the
: shaft and using a strut but I hate to have to
: go through with that also if there is any way
: to get decent performance without doing so.
: Undoubtedly the Yankee 30 was not designed to
: be a great power cruiser. There is a problem
: with the prop so close to the keel and such
: limited space to swing with respect to the
: bottom of the hull just above the prop.
: However, I am hoping to do a bit of traveling
: in this boat and I would hate not to have
: reasonable performance under power also.
: I am now calling all good Yankee owners to my
: assistance with advice. I would love to know
: what props you are running on your boats at
: what shaft rpms and what performance you are
: getting. Any and all opinions and
: information much appreciated.
: In the meantime Happy Holidays... Carl Seipel
:
:
Hi Carl,
Glad to hear that you got the boat back in the water. Sorry to hear that motoring performance isn't what you'd hoped with the engine swap. My situation is a little different, so I don't know if it will be of much assistance to you. I have a direct drive Atomic 4 with a 12X6 2 blade prop and a strut. I typically cruise at 2,000 RPM at about 5.25 knots. Top engine speed is about 2,400 RPM.
Message Thread:
« Back to thread