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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Motor Mount Specs.

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Keith Dennis
Deckhand

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13 Posts

Initially Posted - 08/02/2004 : 13:56:24

I recently purchased a Catalina 25 and I am needing to purchase a different engine for it. I am looking at a late model 9.9 Evinrude Yachtwin with electric start and alternator. The 4 stroke model weighs 110 lbs. I was wondering if anyone knows what the mounting bracket weight range specs were. Thanks!

Edited by - on

jwilliams
Captain

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USA
357 Posts

Response Posted - 08/02/2004 : 17:46:17

Keith,

That's what I have on Hey Jude, long shaft version. Its a heavy sucker.

My engine mount is the original, tube-type Garhauer mount. It has been rebuilt with bronze bushings, larger diameter bolts, helper springs (see the tech tips section) and thicker side arms. Also, reinforced inside backer made from 7/8 in plywood.

There have been extensive postings on alternative engines and mounts. I think the hot set up is the Honda 8Hp 4S long shaft right now. Look in the archives or someoneanother of our brothers will tip you to the right site.

Jim Williams
Hey Jude C25fk 2958
SF Bay

Edited by - on

Lowell
1st Mate

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USA
30 Posts

Response Posted - 08/03/2004 : 00:50:15

The Garhauer web site says the capacity of their retractable engine mount is 125lbs. I recently replaced my original Garhauer mount with a new one. As someone on this site recommended I used the stainless mounting angles off the old mount as backing plates inside the hull to help distribute the load. I have a 2004 8hp Honda extra long shaft with electric start hanging on it. The owners manual says this motor weighs about 117lbs. I believe it! I've been keeping a close eye on things and so far no problems.

Lowell Heenan
Dreamer 5655

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lcharlot
Master Marine Consultant

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Antigua and Barbuda
1301 Posts

Response Posted - 08/03/2004 : 08:11:32

Another issue with hanging really heavy motors on the Cat 25 transom is "oil canning" of the relatively thin fiberglass. If I were going to mount an outboard weighing more than about 80 pounds, I would install a 16" x 12" piece of 3/8" thick aluminum plate or 3/4" thick Starboard between the transom and the motor mount to spread the load.

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oldsalt
Admiral

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USA
578 Posts

Response Posted - 08/03/2004 : 22:47:56

Show me a Catalina 25 whose transom "oil cans" under the load of an 80 pound outboard and I'll show you a Hunter or a Mac.

However, to effectively strengthen the overall transom structure in the event that a heavy 4 stroke engine is installed, any reinforcement plate would need to be installed as a backing plate on the inside of the transom between the motor mount nuts and the transom, where it can absorb the strain of both the additional static and dynamic loading imposed by the weight and thrust of a motor which exceeds that originally recommended by the factory.

But for any conceivable 2 stroke outboard, let alone one weighing 80 pounds, save the Star Board for cleaning fish.

Edited by - oldsalt on 08/03/2004 23:12:49

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 08/04/2004 : 22:28:02

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by oldsalt
 ...to effectively strengthen the overall transom structure in the event that a heavy 4 stroke engine is installed, any reinforcement plate would need to be installed as a backing plate on the inside of the transom between the motor mount nuts and the transom, where it can absorb the strain of both the additional static and dynamic loading imposed by the weight and thrust of a motor which exceeds that originally recommended by the factory.

But for any conceivable 2 stroke outboard, let alone one weighing 80 pounds, save the Star Board for cleaning fish.

<hr height="1" noshade id="quote"></blockquote id="quote">
I disagree... A large part of the force imposed on the transom will be inward against the lower edge of the bracket, due to the weight of the engine, the leverage of the bracket, and the thrust while in forward gear. An equal force is outward against the upper bolts holding the bracket. The inner lining and outer transom were not designed with these 100+ lb. high thrust engines in mind, and the light foam core between my transom and liner won't contribute anything. I've seen some denting (not exactly oil-canning) on C25 transoms at the bottom edges of the brackets, with lighter engines than mine. That suggests plates on both sides--not just one. I used Starboard for an outer plate that extends well below the bracket, and an inner one that extends as far as possible above it. I'm pleased with the solidity.

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oldsalt
Admiral

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USA
578 Posts

Response Posted - 08/04/2004 : 23:07:35

Dave I agree that ideally, if one wants to beef up the transom area, backing plates should be installed on both sides, particularly if there is a foam cored liner there.

On my '83, Silver Girl, the transom has no inner liner and therefore, no foam core. My transom is solid GRP with a rather heavy mat roving lay up (not chopper gun stuff) and a large area of extra layers of heavy mat extending well beyond the motor mount area.

I have a '96 Sailmaster 2 cycle weighing around 90 pounds, hung on the stock Garhauser mount, and my transom shows no sign of canning or weakness at all.

However if in the future I decide to replace it with a heavier 4 stroke, I'll beef up the transom with plates on both sides as well as upgrade the mount just to be on the safe side. But with my current setup, my transom is stiff as well as rock solid.

Edited by - oldsalt on 08/04/2004 23:09:47

Keith Dennis
Deckhand

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13 Posts

Response Posted - 08/10/2004 : 12:00:45

I got a 2005 Yamaha 8 HP instead of the 9.9 Evinrude. It is electric start with alternator and weighs in at about 105 lbs. I am going to put plates on both sides just to be on the safe side as well. Thanks for all the good advice!

Edited by - on

roberoo
Navigator

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USA
182 Posts

Response Posted - 08/10/2004 : 19:50:55

I am not sure what the actual physics/engineering are. But earlier this year I followed what Frank Hopper had done to his boat and put a sandwich of starboard and a Garhauer mount on the transom. It is holding up the XL shaft 9.8 4 stroke Nissan motor and I use it at 3/4 throttle pushing the boat at about 6knots with no problems. I also put a starboard backing plate inside the transom.

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.