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Raising long shaft outboard motor for inflatable boats designed for short shaft engines.

Posted by   Eliot
03/28/2014
Raising long shaft outboard motor for inflatable boats designed for short shaft engines.

For the past few months I have been searching a variety of forums and outlets for a new toy come spring. I had a few RIBs in mind and hadn't given too much thought to inflatables until I came across Saturn's 15 foot model - the SD470 inflatable boat. Its not often stumbles upon a boat with a low transom that is designed for an 15" inch shaft on the motor, let alone one that can be deflated and packed away when I am done. I am an avid spearfisher and I frequently find myself with a need for maximum horsepower once I am outside the marina.

The waters out here on the Pacific coast have some pretty decent current and swells to them so most of the more adventurous boaters who do venture out on them tend to keep their motors performing at peak so having something with a shorter shaft is really ideal for those of us who need the increased maneuverability and handling. I've tried using 20" inch shaft motors - a 40HP I had laying around from a few summers ago and I found that even by raising it a little with a jack plate I still encounter some rough turning at higher speeds plus the drag from all the extra prop being down makes the ride too choppy for my tastes.

I enjoy the excitement of rushing across the swells so to have the motor sit high is a real benefit for me so I
try to leave the prop just deep enough to not blow bubbles and I am cruisin' happily. I've taken control a few times of Seamaxx equipped with a 3" Jack plate and have never been able to achieve the control I
really want to. The boat always feels heavy in the water and really bogged down when the gas is delivered. Many people say that your top end speed will suffer when using a short shaft motor but I inclined not to agree. Perhaps because the boat weighs nearly as much as I do there isn't much slowing me down. Now I am able to be well past the markers before the wife even notices that I am gone!

Here is links to those jack plates that I have used:

T-H Marine Hi-Jacker Fixed Jack Plate

TH Marine CMC 2 Piece Manual Power-Lift Transom Jack 4" Setback