I purchased a CD25 last fall and have been sailing it out of Shelter Island NY this season. The motor that came with the boat ('89 2-cycle 9.9hp Evinrude) is somewhat unreliable so going to replace it. In looking through the postings on the board, I have noticed that many people have a 6hp Tohatsu for their CD25. I have found a good deal on a used 4hp 4-cycle Tohatsu and was wondering if anyone on LI Sound has used a 4hp for a CD25 and if it has enough power. I typically use the motor only to get out into Gardiner's Bay.
Thanks
Steve
4hp for CD25
Moderator: Jim Walsh
You may be underpowered going against the weather
I had a week of sailing with a friend this summer on a similar boat (Paceship Eastwind 25, 4500 lbs, full keel).
His 4 hp 2-stroke was fine in calm wind and waves, but it couldn't do very well against a headwind > 10 knots, or waves of more than a foot or two.
This is my former boat, and I used to have an 8 hp outboard on it. It definitely punched through the weather much better.
I think 6 hp could be a good all-around choice.
His 4 hp 2-stroke was fine in calm wind and waves, but it couldn't do very well against a headwind > 10 knots, or waves of more than a foot or two.
This is my former boat, and I used to have an 8 hp outboard on it. It definitely punched through the weather much better.
I think 6 hp could be a good all-around choice.
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sfreihofer
- Posts: 223
- Joined: Dec 6th, '07, 22:05
- Location: 1981 Cape Dory 25 #794, S/V PEARL
- Contact:
I'm wondering if there is a power prop available for that 4 hp engine. Most outboards come equipped with a speed prop, which isn't optimal for a displacement hull. A power prop has a larger diameter, but a smaller pitch.
The 8 hp Yamaha that came with my boat had a speed prop, and I have changed it to a power prop. Unfortunately, I can't attest to any change in performance since the boat hasn't hit water yet.
A power prop may help, but there's no getting around the fact that 4 horses can't do the work of 6 or more.
The 8 hp Yamaha that came with my boat had a speed prop, and I have changed it to a power prop. Unfortunately, I can't attest to any change in performance since the boat hasn't hit water yet.
A power prop may help, but there's no getting around the fact that 4 horses can't do the work of 6 or more.
Instant Bubble-head. Just add water.
engine combination
I have a Tartan 26 (5,200# displ fin keel).
After I bought it, I wanted to take her out before I brought her home to work on her. The existing inboard engine, a 5 hp Kermath Sea Pup (some later boats were built with Vire 7 hp) needed work, so I made up a temporary motor mount to hang on the transom. Upon it, I placed a Honda 5 with the lower pitch prop (two props available for that OB).
My finding was that in a light breeze, maybe 10 kts, it seemed to be adequate in forward, but it failed miserably in reverse, probably due mainly to a throttle limit built into the OB for reverse (a safety device, as near as I can tell) that limits reverse RPM's to a fast idle. Anyhoo....in reverse there wasn't enough thrust to move the boat against that 10 kts. Similarly, reverse was inadequate for slowing the boat.
For some people, the OB would be adequate, but for the places I expect to take the boat (crowded, convoluted marinas, etc) I would want reverse to have more umph.
[img]http://www.htmills.com/images/LF-Tartan04lowering.jpg[/img]
After I bought it, I wanted to take her out before I brought her home to work on her. The existing inboard engine, a 5 hp Kermath Sea Pup (some later boats were built with Vire 7 hp) needed work, so I made up a temporary motor mount to hang on the transom. Upon it, I placed a Honda 5 with the lower pitch prop (two props available for that OB).
My finding was that in a light breeze, maybe 10 kts, it seemed to be adequate in forward, but it failed miserably in reverse, probably due mainly to a throttle limit built into the OB for reverse (a safety device, as near as I can tell) that limits reverse RPM's to a fast idle. Anyhoo....in reverse there wasn't enough thrust to move the boat against that 10 kts. Similarly, reverse was inadequate for slowing the boat.
For some people, the OB would be adequate, but for the places I expect to take the boat (crowded, convoluted marinas, etc) I would want reverse to have more umph.
[img]http://www.htmills.com/images/LF-Tartan04lowering.jpg[/img]
Tod Mills
Montgomery 17 "BuscaBrisas", Sandusky, OH (with trips elsewhere)
Tartan 26 project boat
Cape Dory admirer
Montgomery 17 "BuscaBrisas", Sandusky, OH (with trips elsewhere)
Tartan 26 project boat
Cape Dory admirer
I have a Nissan 4HP 4 Stroke. It's fine in the Bay. The Tohatsu is the same motor. I read on a Nissan Dealer's site that the 4HP can be upgraded to a 6HP by simply upgrading the Carb. It's on my list. When in the Ocean I would like the extra push.
I there are a couple of prop options. I can't remember what the pitch is on mine, but it was set up for a heavier displacement boat.
I there are a couple of prop options. I can't remember what the pitch is on mine, but it was set up for a heavier displacement boat.
Seajunkie
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tartansailor
- Posts: 1528
- Joined: Aug 30th, '05, 13:55
- Location: CD25, Renaissance, Milton, DE
Outboard in Reverse
There are 2 reasons why Outboard in Reverse have minimal thrust:
1) Inherent design in the (any) prop.
Now if you do not believe that, just try and reverse the props on a twin screw power boat with counter rotating drives; and see what you get.
2) Under water exhaust gas gets pulled into the prop; and now the prop
has less water to "bite"
Dick
1) Inherent design in the (any) prop.
Now if you do not believe that, just try and reverse the props on a twin screw power boat with counter rotating drives; and see what you get.
2) Under water exhaust gas gets pulled into the prop; and now the prop
has less water to "bite"
Dick
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Carl Thunberg
- Posts: 1307
- Joined: Nov 21st, '05, 08:20
- Location: CD28 Cruiser "Loon" Poorhouse Cove, ME
Anchor Setting Implications
Thank you, Dick for that explanation. It makes sense. Not wanting to hijack this thread with another topic altogether, but this confirms what I've always thought about small boats with outboards. I've always felt it was better to have a small anchor because you have so little thrust available to set the anchor with. I'd feel much more secure with a properly set small anchor than I would with an oversized anchor that you can't possibly set (i.e. undersized mooring). Just a little more food for thought on the horse power topic.
CDSOA Commodore - Member No. 725
"The more I expand the island of my knowledge, the more I expand the shoreline of my wonder"
Sir Isaac Newton
"The more I expand the island of my knowledge, the more I expand the shoreline of my wonder"
Sir Isaac Newton
Honda linkage
Tartansailor,
The Honda 5 also is designed with linkage that limits how far the throttle will twist. When in FWD, the throttle will turn all the way. In N or REV, it will only turn to fast idle.
(not that this fact negates your good points)
Tod
The Honda 5 also is designed with linkage that limits how far the throttle will twist. When in FWD, the throttle will turn all the way. In N or REV, it will only turn to fast idle.
(not that this fact negates your good points)
Tod
Tod Mills
Montgomery 17 "BuscaBrisas", Sandusky, OH (with trips elsewhere)
Tartan 26 project boat
Cape Dory admirer
Montgomery 17 "BuscaBrisas", Sandusky, OH (with trips elsewhere)
Tartan 26 project boat
Cape Dory admirer
