Association Forum - Outboard Shaft Length

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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Outboard Shaft Length

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JanS48
Navigator

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USA
149 Posts

Initially Posted - 09/10/2026 : 22:16:24

Hi everyone, on my C25 I have a Honda 9.9 with an extra long shaft. I'd like to replace it with a an older Honda 7.5 which has very low hours on it but it's just a long shaft, not extra long shaft. From the clamp to the plate above the prop measures 23 inches on the 7.5
Is that going to be long enough ?
I know originally when I got the boat it had an 8hp Nissan 2 stroke long shaft but I never used it.
Thoughts ?

82 C25 SR FK
Sailing out of Newport Harbor.

Steve Milby
Past Commodore

Members Avatar

USA
5935 Posts

Response Posted - 09/11/2026 : 09:49:02

I'm not 100% sure, but you want it to be long enough so that the cavitation plate stays submerged all the time. One way to test it is to put a person weighing about your weight on the bow of the boat. That will lift the transom. Then measure down 23" from the top of the motor mount. If the end of your measuring device is about 3" under water, I think it would be sufficient at least on an inland lake. If you get into bigger, choppier waters, I think you need the longest shaft you can get. If it's less than 3" it's likely that the prop might lift out when motoring while someone is working on the bow.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

OLarryR
Master Marine Consultant

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USA
3522 Posts

Response Posted - 09/11/2026 : 21:19:12

What Steve suggested sounds like a good idea.

I also have a Honda 9.9HP XLS. I also have a 4 spring Garhaer outboard motor bracket. Many (but not all) Cat25s have this same bracket. The bracket has two lowered positions that it can be locked in but the lower position is the appropriate running position in almost all instances. I mention this because you could test run in forward and reverse your Honda XLS in both the lower locked position and in the slightly higher locked position. You could measure the difference in inches that higher locked position is compared to when the outboard is in the lowest locked position and see if the higher locked position would be close to simulating the length of a LS versus an XLS outboard. Then see how it runs.
I had perhaps a couple of times, ran my outboard in the higher locked position (mostly if I had not secured the bracket in the lowest position and it slipped so for a very short time secured it in the higher position) and the outboard sometimes would cavitate depending on the waves/ripples in the water. Also, there is another issue besides the prop cavitating, the lower end has to be sufficiently in the water so that the outboard is cooled appropriately - water intake not to be compromised.

I forget what the differences are in the lengths between a typical XLS and a LS, It is possible that my suggestion above will raise the outboard more inches than the difference between the length of an XLS and a LS.....so rcmd check the height change between the two lower locked positions.

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

Edited by - OLarryR on 09/11/2026 21:22:28

JanS48
Navigator

Members Avatar

USA
149 Posts

Response Posted - 09/12/2026 : 06:06:51

Thanks for the input, I've decided to keep the extra-long shaft Honda 9.9 on the boat.

82 C25 SR FK
Sailing out of Newport Harbor.

Steve Milby
Past Commodore

Members Avatar

USA
5935 Posts

Response Posted - 09/12/2026 : 07:39:36

FWIW, I had a Honda 9.9 and it's a great motor but terribly heavy. You might want to keep an eye out for a good used 4 cycle Tohatsu XL 6 or a Merc XL 6 or a Nissan XL 6. They're all made by Tohatsu, only weigh 59 lbs., and are a good choice for a 25' boat. You might lose about .5 kt top speed, but the light weight and very stingy fuel usage is a huge plus.