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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Outboard Shaft Length

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JoergK
Navigator

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USA
140 Posts

Initially Posted - 04/09/2003 : 11:16:44

I am about to buy a new (used) outboard, got an offer for a 9.9 with a 20" shaft. Is this long enough or do I need an x-tra long with 25" ?

Joerg
86C25 SR-SK Second Wind

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Derek Crawford
Master Marine Consultant

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USA
3312 Posts

Response Posted - 04/09/2003 : 11:29:28

Joerg - buy the longest shaft O/B available. In even the smallest chop the 20" shaft will cavitate a lot of the time.
Derek

<img src="http://im1.shutterfly.com/procserv/47b3dc30b3127cce942c608d6f1e0000001010" border=0>
TRFK#2262"This Side Up"

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dave holtgrave
Captain

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USA
427 Posts

Response Posted - 04/09/2003 : 12:17:57

you'll never be sorry you bought the 25 "
i agree the 20" is alittle short
dave holtgrave
5722
15 days to sailing at carlyle lake in southern illinois

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 04/09/2003 : 12:25:31

I agree with Derek, you need the longest you can get, especially if you sail on large open waters. A short shaft motor will work as a kicker on smaller inland lakes where waves are rarely generated, but for larger waters with the potential for breaking waves, a longer shaft is highly recommended.

I've never measured my prop depth, but a lot depends on the motor mount and how far it goes down. There is a variety of outboard powered sailboats in my marina and the motors run from the smallest motor available to 50hp behemoths. The key is the motor mount. On boats that use a regular shaft motor, the mounts need to be lower, on boats with longshafts the mounts need to be higher.

<img src="http://www.catalina25-250.org/c25sm.gif" border=0>Don Lucier<img src="http://www.catalina25-250.org/c25sm.gif" border=0>
<img src="http://im1.shutterfly.com/procserv/47b2cc32b3127cce92e981259d130000001010" border=0>
North Star SR/FK

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/09/2003 : 21:22:13

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
...a lot depends on the motor mount and how far it goes down.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
That's the key. The shaft length is the dimension from the top of the bracket's mounting board to the anticavitation plate above the propeller. So, how high the bracket is above the waterline (in the down position) is as important as the length of the shaft.

On a small lake with only the occasional boat wake, having the anticavitation plate 1-2" below the static waterline is probably OK--the stern will squat a little under power so a few boat wakes won't bother you. On coastal waters or large lakes with substantial wave action, 4-6" is better. But if you don't have an XL shaft, that puts the powerhead in peril of being bathed by a following sea. With less depth, you get (1) loss of power, (2) nerve-wracking screaming from the outboard, and (3) possibly loss of cooling when the waves cause your boat to pitch. (Remember, with the motor mounted well aft of the transom, the rise and fall is magnified.)

My DPO had a "long shaft" (22") motor and a short-throw bracket that put the anticavitation plate at the waterline. When I went forward of the cockpit with the motor idling, it sucked air into the cooling system. At cruising speed, it squatted about 3" lower, but cavitated in any serious chop. The motor and the bracket were equally to blame. The setup was a waste of his money, and eventually mine.

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette-Honda "Passage" in SW CT

Edited by - Dave Bristle on 04/09/2003 21:24:13

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ronrryan
Admiral

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USA
561 Posts

Response Posted - 04/12/2003 : 19:57:27

I hesitate to opine, because I have been mostly an inboard guy, but have used three or four outboards on sailboats up to 26 feet. I agree the longer the better, but a standard longshaft (20") around here is often found used --very little used--from under a grand to just over. A new 25" extra long shaft might be a thousand more than that. Unless you are going to be in BIG water, that thousand could do a lot of things. I know many will say this is foolish savings, but-----god bless, ron srsk #2343 Orion SW FL

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RichardG
Admiral

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USA
990 Posts

Response Posted - 04/13/2003 : 00:08:53

Joerg:

Much depends on the price of the 9.9, plus its age, condition, etc. And as Don and Dave said, the type and location of the engine mount can make a significant difference.

Whether due to cost, availability or other reason, 20" shaft engines are by far the majority for smaller sailboats around here and most seem to survive reasonably well with them.

While starting the engine and accelarating from a stop, I put the 20" shaft engine on my Garhauer mount to the "lower" setting. Once moving, after the bow has risen (and the stern has dropped), moving the mount to the "upper" setting seems the most efficient running position. If a boat wake causes cavitation, I momentarily reduce the throttle till the wake passes and then move on. If going forward for a while (and if no one remains in the cockpit to compensate), I simply put the bracket on the lower setting before doing so and raise it upon return. Only rarely do short-cycle wind waves in the ocean can cause cavitation, but I can move the bracket to the lower setting (but wind waves means I can probably sail, without the engine). Big swells are usually well spaced and thus don't normally present a cavitation problem. In any event, the shortcomings of a 20" shaft engine are negligable and/or easily mitigatable to me.

Is a 25" engine shaft better -- absolutely. But how much better and how much you are willing to pay for that incremental benefit is the real question.

Edited by - RichardG on 04/13/2003 00:13:18

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77Gypsy
Captain

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USA
356 Posts

Response Posted - 04/14/2003 : 15:16:49

20" should be good, i've never had a problem with any of my boats. it may cavitate a bit if you hit some wake.

Steven de Filippis
78 catalina 25 - Gypsy

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JoergK
Navigator

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USA
140 Posts

Response Posted - 04/15/2003 : 12:34:59

I really appreciate all your observations.
Since I sail (and sometimes have to motor) in choppy waters (there are a lot of powerboats around in Barnegat Bay) I am going for the 25" shaft. Fortunately, for the used engine that I have in my sights, there is a 20" to 25" extension kit available which adds a manageable $190 (plus $150 or so labor) to the price.
Again, thanks.

Joerg
86C25 SR-SK Second Wind

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John Bixby
Navigator

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118 Posts

Response Posted - 04/15/2003 : 15:35:28

I HAVE A 9.9 WITH THE 25" SHAFT. MY PROP HAS STILL COME OUT OF THE WATER IN BAD WEATHER AROUND GALVESTON.
GO FOR THE LONGEST SHAFT POSSIBLE.
JOHN ON MS ACHSA #77

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Gloss
Master Marine Consultant

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USA
1916 Posts

Response Posted - 04/15/2003 : 22:13:21

I am in the 25" camp. I recently purchased a Honda extra long shaft and in heave seas in the Keys it came out a few times. I couldn't imagine having a 20" for anything but calm lakes, and that's with a low slung motor mount too.
In this case, size does matter.
As an interesting side note. On the Catalina 22 discussion website (I still have my 22, hope to sell her soon) someone came up with an interesting analysis in the 2 vs 4 stroke debate. In it he compared the amount of gas you have to carry to be equivilant. A 4 stroke may need a 3 gallon tank, while a 2 stroke would need a 6 gallon to get the same range. A gallon of gas is a little over 8 lbs, so that's an additional 25 pounds of gas to save 25 lbs on a motor. Coincidence?
I replied that you still have to consider how much it takes to lift it. My Honda extra long shaft is a beast to pick up at 108 lbs.

Frank Gloss
89WK/TR

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/15/2003 : 22:42:30

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
My Honda extra long shaft is a beast to pick up at 108 lbs.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
Sure is... But it also starts and runs like a little Civic! Last fall, I had a yard guy with a platform forklift pull it off the boat while it was still on the travel-lift, and I may find him again in a few weeks.

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette-Honda "Passage" in SW CT

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