I'am repowering with a yanmar2qm15, the mechanics manaul for this engine says only to use a single lever dual action controls for the operation of throttle and transmission. my boat currently has a double lever morse mjb ch2500. that worked well with the old motor. Is there any reason why this wouldn't work with the yanmar other than what the mechanic book say's?
The single lever requirement is to force idle speed when shifting from forward to reverse (or vice versa). Two levers will work mechanically just fine, but you run the risk of possible transmission issues if shifting without throttling back.
I had two levers with a 3qm30 on the old boat and it was not a problem. Same with the 3gm30 I have now. To me its easier with two levers, but then I use my feet half the time to go to idle and shift to neutral (I have the old morris two lever controls installed on the lower cockpit sides.)