CD25 Outboard questions Mercury vs Tohatsu

[KDreese]

Sea Junkie, thats interesting about the motor mounts. I dont think I have room to move mine back 8 inches... I wonder if either yours or mine were moved from the original position?

[Maine Sail]

thats right,

mercury, mariner, nissan and tohatsu,

Mercury dropped the Mariner line years ago. The early ones were made by Yamaha. Mariner was part of Mercury like Johnson & Evinrude were to each other.

tthere are two others to add to the list, one is from canada and not honda....

The big name, legitimate manufactures of small outboards still selling in the US are. Suzuki, Tohatsu, Nissan, Mercury, Honda & Yamaha.

Johnson's smallest outboard today is a 9.9 hp four stroke made by Suzuki. Evinrude only makes large motors.

tall of there blocks are the same for all out boards and all external parts are made from someone else...

That statement is not totally accurate. yes all the blocks are the same for Nissan/Tohatsu/Mercury up to about 10hp+. These motors are all built by Tohatsu.


As for "all of there blocks are the same for all out boards";

Yamaha builds Yamaha motors and has no shared blocks with Tohatsu. Honda builds only Honda motors and does not share their block. Suzuki builds Suzuki's and sells only the 9.9 to OMC/Johnson..

The only motors that share blocks & parts or are identical are the small Mercs, Tohatsu's and Nissans.

[river-rat]

My 1977 CD25 # 484 required modification of motor mount to fit a Nissan 6 HP 4 stroke. It does allow some motor rotation to assist in steering (especially in reverse).

After a long wait for a low pitch prop from Nissan, I obtained a 6 inch pitch from Mercury. With the extra long 25 inch shaft, steering and handling have been adequate.

Note that the latest Nissan web site shows a 8.375 dia X 6 pitch sail drive prop. I have discussed this with Nissan by phone to get their take on possible improvement. I did not get a useful answer.

Because the increased diameter represents about a 13% increase in prop area, a slight improvement may be possible. I suspect that the motor does not reach full rated RPM with the 7.9 inch diameter. The expense of the larger prop ( $64) may not be worth the change.

[seajunkie]

My 1977 CD25 # 484 required modification of motor mount to fit a Nissan 6 HP 4 stroke. It does allow some motor rotation to assist in steering (especially in reverse).

Do you have any pictures of your modifications? Can you fit the tiller through the door with the hood down? I can't get my hood to close and I took a significant chunk of wood out of the mount.


I will take some pictures of my motor well modifications tomorrow if I'm allowed to go out and play.

8" might have been an exaggeration. It is very far forward.

[pete faga]

The wells are different as cape dory made changes through the run years(windows changed about hull 250?) I think the motor well and hood also changed about then. So refits will be different according to year/hull#. Grace is hull #66 and i repowered with the tohatsu 6 20" shaft which fit in ok .The hood almost closes all the way.I just use a sample carpet piece that goes ontop of the engine to protect the engine top.

[pete faga]

The wells are different as cape dory made changes through the run years(windows changed about hull 250?) I think the motor well and hood also changed about then. So refits will be different according to year/hull#. Grace is hull #66 and i repowered with the tohatsu 6 20" shaft which fit in ok .The hood almost closes all the way.I just use a sample carpet piece that goes ontop of the engine to protect the engine top.

[KDreese]

Thats a good point about the hull years and the different lids. Mine is a 1974 and the lid does not have a core in it (its just solid fiberglass). I believe that some time after 1974 they added cores to the lids so I wonder if that would make the lid thicker and therefore require more clearance.

[tartansailor]

My 1975 definitely does not have a core.
In order to get my 8 hp Honda to fit, 2" blocks
were placed between the hinges and the deck.
That by the way solved the make up air need.
Dick

[seajunkie]

Here is my mount. My 2005 Nissan 4HP four stroke still protrudes over the hood. Click on thumbnail for larger picture.

[KDreese]

Sea Junkie,

Your mount looks about 1 to 2 inches higher than mine. Mine at its highest point is a little lower than flush with the gas can shelf. From the picture it looks like the top of mine would be in line with the lowest part of your cut out section.

[seajunkie]

Mine at its highest point is a little lower than flush with the gas can shelf.

That's interesting. I fabricated a block of wood that sat lower. The problem then was that the (for lack of a better word) bolts that torque down the motor wouldn't turn all the way. They would butt up against the bulkhead in front of the motor.

[KDreese]

Unfortunately I wont be down to the boat till next Saturday, but I will take a picture of my mounts. I dont have a good one to post to show how it looks on my boat.

[tartansailor]

The top of my OB motor mount is 2 & 1/2" above the bottom of
the access well. (The wash board sets on top of that).
On top of the mount sits an 8 hp Honda.
The SS angle iron you see faces forward, and is as forward as
much as possible.

Dick

[img]http://i76.photobucket.com/albums/j19/t ... 0_0249.jpg[/img]

[Carl Thunberg]

I'm curious why folks would think they need more horse power on a CD25. My previous CD25 had the 6HP Tohatsu and I never once felt underpowered, and I was moored in the Piscataqua River, which has a pretty nasty current. I could always make decent progress even in an adverse current, and once I cleared the entrance to Portsmouth Harbor, I could sustain boat speeds over 5 knots. I just don't see why you'd need more power than 6HP if you have the correct prop. More horse power is more weight aft and more up-front cost. Am I missing something?

[tartansailor]

You are right, 8 hp is way too much weight.
I believe the ideal for a CD 25 is a 4 hp 2 stroke
with a 5" pitch prop.
IMHO Dick