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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Transom Support for Motor

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BSY On Genesis in Vallejo
Deckhand

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4 Posts

Initially Posted - 09/13/2002 : 23:44:39

First, thanks to all that have given advice on motor mounts for the new 4 stroke engines. I just purchased a Fulton 1810 for our new Honda 9.9 (way more HP than needed for the C-25).

My question is, will the transom support the new 4 stroke engines?

I know there are a lot of engines hanging on C-25 transoms but are they designed for the heavier engines? Looking at the construction of our C-25 (hull 5960) the boat liner is supporting the bolts for the motor bracket. The construction for my boat has a hallow transom, a 1.4" space and then the internal boat liner. The motor bracket bolts go through the transom, through the 1/4" space then through the liner where I've installed a 3/4" plywood backing plate and then the nuts. The transom supports the downward moment from the bolts but the liner supports all pulling weight of the engine.

At this time, I'm considering removing the motor bracket and filling the transom with fiberglass resin/chopped glass. Then installing a 1/4" plywood filler between the liner and transom.

What are your experiences and/or thoughts?????????

Edited by - on

n/a
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125 Posts

Response Posted - 09/13/2002 : 23:52:44

Hey,BSY sorry I don't have anything worthwhile to add to your mount issue. Interested in location....are you moored in Vallejo, or on a trailor. If moored where. I have a c250 that I keep at Berryessa, and I'm considering putting it in salt next year....Benicia's high, Glen Coves kinda full, I would appreciate some response, Thanks

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Brooke Willson
Admiral

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USA
983 Posts

Response Posted - 09/14/2002 : 11:32:57

A hollow transom? I'm not sure what you mean. The transom on my 1985 C25 is layered, but hardly hollow. If there's a gap between the outer and inner gelcoat on your transom, it sounds like something is very very wrong.

I also don't think it's accurate to say that the liner supports the motor mount. Because of the relative thicknesses, I think the transom supports the weight of the motor much more than the liner.

I have a 2 stroker on my boat, but there are plenty of C25 owners with 4 strokes who seem to have had no problem whatsoever. My experience is that while it's not a bluewater boat, the C25 is reasonably overbuilt.

Brooke

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dave andersen
1st Mate

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85 Posts

Response Posted - 09/14/2002 : 13:29:01

I know you have your 9.9 honda but for others let me highly
recommend the 8hp Yamaha 4 stroke -- weighs 81 lbs -- very good
power for the C 25 -- I sail in the Pacific off Ventura.
Check it out. Shift lever high up on the tiller ( no leaning over
to shift) a great flush valve right next to the tiller.
Best outboard I've ever had.

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 09/14/2002 : 14:16:53

BSY,

Although I have a much earlier hull number (1460), I'll try to describe how my transom is reinforced at the motor mount.

My motor is mounted on the port side. From the factory, the transom has a plywood core, maybe 3/8" or 1/2" thick. The hull liner overlaps the area of the transom where the motor mount attaches, similar to what you described. When I got my boat (used of course), the motor mount installation was reinforced by two large stainless steel plates maybe 1/8" thick. One plate was between the mount and transom, the other was inside (forward) of the hull liner. This didn't really directly address the gap between the transom and liner.

What I did was to omit the inner stainless steel plate. Using the largest holesaw I have (maybe 3" or so), I drilled through the liner only, *but not the transom*, at each of the four motor mount bolts. I also cut four "cookies" from a scrap of 3/4" plywood using the same holesaw. Each of these plywood disks was saturated with two coats of epoxy. Then they were bonded to the forward face of the transom at each mount bolt hole, through the holes in the liner. Temporary bolts coated with wax were used to provide clamping force through the boltholes. A generous amount of a putty consisting of reinforced epoxy was used to fill and filet the saw kerf gap between the cookies and the liner.

This modification has been in use for about two years so far with no signs of cracks or other problems developing. The heaviest stress I think it has endured was running 5' chop in an ocean inlet, which resulted in the spinning prop (of the Yamaha 9.9HP hi-trust, extra long leg) being lifted in and out of the water many times while running at least half throttle.

-- Leon Sisson

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 09/14/2002 : 23:01:44

My '85 has a foam-cored transom with the outboard bracket on the starboard side. Hoever, there is no core below the ledge aft of the quarterberth. I mounted the bracket above the ledge. I put a fairly large 1/2" King Starboard (plastic) plate under the bracket on the outside of the transom, and another piece of Starboard inside as a backer. The outside piece is meant to spread the load across a larger area of fiberglass than the small footprint of the bracket would have. It also contributes a little to moving the bracket away from the transom, which is necessary with the 1810. I suspect my setup is substantially overengineered, but I can't think of anything wrong with that. Starboard is amazingly easy to work with ordinary power or hand wood tools and comes in other thicknesses.

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

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BSY On Genesis in Vallejo
Deckhand

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4 Posts

Response Posted - 09/15/2002 : 12:06:24

First: We are located on "F" dock in the Vallejo Marina. After spending several years trying various marinas the Captain and I selected Vallejo because of driving time from Reno, the VERY friendly management (City workers) at Vallejo, clean restrooms, ability to sail even when the Bay is fogged in or Bay winds are +30mph and other. We looked at marinas from Bruno's (Delta) to the South Bay. Vallejo is first class. We use to have a C-250 W/B (great Bay boat) and our friends are on the same dock with us and they have a C-250 W/K.

Second: Thanks for the replys to my question. I think my plans will combine the Starboard and filling the space inside the transom. I will also look at cutting the *"liner"* to bypass the load at this location. Suggestion for vendor's for Starboard?

The suggestion for an 8hp is also very correct. Anyone want to buy a new Honda 9.9?

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 09/15/2002 : 15:54:46

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>

The suggestion for an 8hp is also very correct. Anyone want to buy a new Honda 9.9?
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
It's correct if you don't want electric start, extra-long shaft, and high-thrust. If you want any or all of those things, the Yamaha is a couple of pounds heavier than the Honda, has no manual starter (without getting out the wrenches), still has a shorter shaft, and has half the alternator output. Otherwise, it's a nice engine--the fresh water flush is indeed a little more convenient than the Honda's.

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

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