transom height

[D Grass]

I have a 1960 15 horse mercury and I was wondering how to measure the the shaft length. I know a short shaft is supposed to be 15 and a long shaft is supposed to be 20. I know this isn't a long shaft, but I was wondering if there was a "medium" shaft length 40 years ago. If I am measuring right I come up with a 17" shaft length. I am wondering because I plan on building a jon boat for it and I was going to make the transom 15" but after this measuring fiasco I thought maybe I should make it higher.<br />Thanks in advance for any opinions.

 

[tashasdaddy]

Re: transom height

you measure from the transom clamp ( where the motor sits on transom to the Cavitation plate) the cav. plate should be even with the bottom of the boat.

 

[Chinewalker]

Re: transom height

However, on a 1960 15hp (model 150) the transom clamp to cav plate measurement would be at an angle and would be slightly exaggerated. The 150s had the Glide-Angle drive used on most small Merc twins of the day. To be more correct the measurement should be taken from the plane of the clamp bracket to the plane of the cav plate, vertically, not at an angle...<br /> That said, it is better to run that unit a little deep than a little shallow. It has the automatic transmission lower unit with the water pump up high in the motor leg and it needs to sit a little lower in the water, particularly at start-up, to assure a good prime. Also, the water intake is on the underside of the cav plate and needs to be kept wet to pump.<br /><br />- Scott