cmarks

[cmarks]

Yanmar SD20, contact with an object, now no thrust. Prop appears ok (folding), no unusual noises (broken shaft). Help.

[boatpoker]

Prop spinning on shaft ? shear pin ? key stripped ?
a

[cmarks]

Thank you boatpoker, I've been scanning the schematics for the afore mentioned sheer pins etc, so thankyou for the info. Out we come asap, cheers.

[GordMay]

Greetings and welcome aboard the CF, cmarks.

See ➥ Yanmar SD20

[skipperpete]

The link Gordmay posted is very informative and the SD 20 is a really good Saildrive. Some folding propellers for saildrives have a rubber element between the hub and propeller as an anti shock device to protect the splined shaft ( google "lost propeller on Saildrive") Gori and Flexofold both have this element and a prop strike will cause it to slip and lose drive. There is also a chance that the splined collar that connects the upper and lower assembly drive shafts has failed , these also may have the torque limiting insert.
But before you haulout there is possibility that the pin linking the shift lever to the selector wedge has sheared off. It's accessible by removing the complete shift assembly. It's a long shot but it has happened before ( the pin dropped out , not sheared off).
Good luck , I'm interested to know how it works out for you ...and hope not too expensively.

[cmarks]

Thank you skipperpet, will checkout Google etc. I have disconnected the gear shift cable from selector arm and it feels as though the selector wedge is engaging, but will revisit. I disconnected the cable to also ensure the lever was not rotating on shaft. The propeller is a Slipstream folding which does have "Side thrust plates" rubber and rubber " bump stop pads. All of which probably helped save the prop.
A very good site for the schematics of the SD20 is; j109.org, the entire address is j109.org/docs/ya mar-SD20-parts-catalog.pdf
It comes up with a company name "Lokken Smede & Maskinvaerksted.
Will keep you informed, cheers.