CD Typhoon Senior outboard fit

[John Stuart]

Help we are trying to fit a new engine to replace merc7.5 which is woefully underpowred. An older Johnson9.9 and a new Merc9.9 will not fit in well. Would appreciate hearin from others about their experiences regards size of engines used etc. Thanks



stuartj@capecod.net

[Kurt]

There must be a mechanical problem with the Merc 7.5 or your speed expectations are incorrect. I estimate the hull speed of the Senior to be around 5.4 knots...it shouldn't take more than about 2 or 3 hp to push the boat along at that speed, in calm water. Anything larger than even a 6hp motor is simply not needed.



kjlgpw@aol.com

[Dick Sisson]

I totally concur with Kurt. My Ty WE (small Ty) displaces about 2000#. About half throttle on a 2.5HP Nissen puts it up to about hull speed. What does a Ty Sr displace? I determine "about hull speed" to be where additional throttle results in no discernable increase in RPM.

What is the motor mount arrangement on a Senior? Is there a removable bracket over the transom like the small Ty, or is there a well? If a well, is there a plug to go in the bottom of the well if you have removed the motor?

I may move up, and the aesthetic/efficiency considerations of being able to stow the motor are a factor to me.

Kurt, what do you estimate for hull speed for the small Ty?



dickee03@yahoo.com

[Kurt]

hull speed = square root of waterline length multipled by 1.34...For the Typhoon it would be the square root of 13.5(3.67) X 1.34 = 4.9 knots. I sail a CD26 (#6000 as she sits in the water) powered with a 9.9 Honda...barely cracking the throttle gets me up to hull speed in calm water



kjlgpw@aol.com

[Don Carr]

There must be a mechanical problem with the Merc 7.5 or your speed expectations are incorrect. I estimate the hull speed of the Senior to be around 5.4 knots...it shouldn't take more than about 2 or 3 hp to push the boat along at that speed, in calm water. Anything larger than even a 6hp motor is simply not needed.

I would tend to agree that a 19Ft boat does not need more than 6 or 7 HP. However, depending where you sail you may have seas or currents running (The Race on LI Sound..2.8-3.5 knots) which nullifies all the theoreticals. 5hp should be more than enough power for basic docking and still water movement.



carrd@erols.com

[Dick Sisson]

...you can't plane these relatively heavy Cape Dorys like you can a MacGregor. You can mount 6 or 7 HP or 20 HP plus or whatever on your "19Ft boat" if that's what turns you on, but if your "19Ft boat" is a 2000# displacement CD Typhoon, your High HP will just churn, vibrate and make noise, trying to push the boat up over its own bow wave, pretty hard to do, Don. It is not likely to push the boat much past "hull speed".

I sure wouldn't let you do any such thing on my boat because all it would accomplish would be to bend and fatigue the bracket.

The point Kurt and I are making is that it dosen't take much HP to push these effecient CD's up to their "hull speed".

Go back and read my previous post. It is my experience that even 2.5HP is overkill for the particular "19Ft boat" I refer to.

Probably not the best configuration of boat for running up the rapids either. Forget that.

Sincerely,

Dickee



dickee03@rivnet.net

[Don Carr]

...you can't plane these relatively heavy Cape Dorys like you can a MacGregor. You can mount 6 or 7 HP or 20 HP plus or whatever on your "19Ft boat" if that's what turns you on, but if your "19Ft boat" is a 2000# displacement CD Typhoon, your High HP will just churn, vibrate and make noise, trying to push the boat up over its own bow wave, pretty hard to do, Don. It is not likely to push the boat much past "hull speed".

I sure wouldn't let you do any such thing on my boat because all it would accomplish would be to bend and fatigue the bracket.

I absolutely agree with you. I am running a 9.8 on my CD25 (#4000) lbs. I can push at hull speed at only slighly over idle. The most one would need on the Typhoon would be 5 hp. When I am coming into my port against the tide running through a narrow inlet I generally crank it up to maintain steerageway and control. The current in that situation is running at 3-4 knots.

Regards.

Don

The point Kurt and I are making is that it dosen't take much HP to push these effecient CD's up to their "hull speed".

Go back and read my previous post. It is my experience that even 2.5HP is overkill for the particular "19Ft boat" I refer to.

Probably not the best configuration of boat for running up the rapids either. Forget that.

Sincerely,

Dickee

carrd@erols.com