4-CYCLE OUTBOARD FOR A CD25

[Wesley Rosario]

I HAVE READ THE OLDER POSTINGS AT THIS SITE REGARDING OUTBOARDS FOR THE CD25 WELL. I LOVE MY BOAT EXCEPT FOR THE FUMES THAT COME FROM MY JOHNSON 9.9 2 CYCLE (AND LACK OF ENOUGH HEAD ROOM WHILE STANDING IN THE CABIN). APPARENTLY THE CD25 CAN HANDLE UP TO A 15 HP MOTOR. MOST PEOPLE SEEM TO HAVE 9.9 OR LOWER. MOST COMPANIES ARE PUTTING OUT 4 CYCLES SINCE THE 2 CYCLES MAY BE LEGISLATED OUT FOR ENVIRONMENTAL REASONS. I SAIL IN BUZZARDS AND NARRAGANSET BAYS IN MA AND RI. ANY THOUGHTS ON GETTING A 15 HP 4 CYCLE THAT WILL FIT THE WELL WITHOUT MAJOR MODIFICATION AND IS LIGHT ENOUGH? ALSO ANY THOUGHTS ON SHORT VS LONG SHAFT AND TYPE OF PROP? THANKS TO ANY CONTRIBUTOR.



wrmd@mybluelight.com

[Dana]

Of course many of the boats were designed for the space of a 2 cycle, 15HP...but that was because a couple of the manufacturers (Evinrude and Johnson) had a 2 cycle engine design where both the 9.9 and 15 HP were essentially the same motor with the exception that the cylinder block was bored larger for the 15HP version. In general, four strokes have larger heads, weight more, etc. for the same horsepower but generally at lower rpms. Thus to compare the space requirement in strictly terms of HP is not valid. Since the time of the 2 strokes, much has occurred to develop high thrust 4 stroke engine models (lower RPMs, same overall HP, larger diameter props/shallow blade pitch), etc for high displacement hull designs. So many have settled on engines like the 8HP 4 strokes on the CD25 to give them the thrust force, physical size needed, gas economy, etc. My own Yamaha 9.9 is known to have the same thrust (push force) as 2 cycle engines up to 30HP. It is just that this thrust only goes up to 9.9 hp of work. but the four stroke engines are a better match for displacement boats which require more thrust but much less boat speeds than power boats.

There is quite a bit of variance in weights between manufacturers for the 8HP 4 stroke. For instance the new Yamaha 8HP 4 stroke wieghts more than my 9.9 Yamaha 4 stroke. Some of the new Evinrude/Johnson 4 strokes are very heavy and large IMHO. Because Buzzards Bay is noted for that 3 foot, short wave length "chop" out of the southwest I would suggest the four stroke, high thrust, 20-25 inch skeg, approx 8 hp.



darenius@aol.com

[isaac]

I am the CD25 owner with a 2 cycle 15HP. It's a mercury. I know you are looking for a 4 cycle, but if you were interested in the 15HP 2 cycle I can tell you that the power is great. Only problem is you cant turn the engine once it is in the well, it just barely fits. This is only a problem when docking in high current areas, my boat has difficulty turning with just tiller.

Good luck, please update on your new engine as i will be replacing soon.