Backing plate for shaft strut

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Jim Logan

Do all of you with 33's have a backing plate on the shaft strut on the inside of the boat? Mine just has large washers, maybe that is why I have leak every now and then?
 
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steven f.

one more thing to worry about

I'm not sure, I even had the boat hauled for a bottom job recently. Now I'll have to crawl back under there and have a look. It's a tight squeeze back there by the rudder post, I'm not sure if I've ever even noticed how the strut is mounted on the inside. My 1981 H33 had been completely dry until she was hauled. I appeared to have burned out my lasdrop dripless drive shaft seal (installed in 1985!) by not burping it after she was spashed. Now the only water in my bilge is from the leaking shaft seal while at high RPM's.
 
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Tim Schaaf

wood

The strut on my 1980 came with a wooden backing plate, that I eventually changed for a thick aluminum one. I feel much better about the installation and it never leaks, something I could not say for the old!
 
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Ed Schenck

Just washers originally.

On my 1979 H37C that is. I loosened them and rebedded under the strut and into the holes. Then I doubled up with another set of much larger washers. No leaks so far. But a backing plate is a much better idea. Rainbow Chaser improved on that. He welded a bar to each of the bolt heads and put the bolts in from the inside. The bar would hit the hull and keep the bolt from turning. Now with the nut on the outside he can tighten the strut anytime, even while in the water.
 
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Sam Lust

Funny you should mention that - - - -

I am currently in the process of correcting the great halyard/strut incident of fall 2000. Let it suffice to say that Stayset X does not break, and replacement struts from Dahmer Marine here in New Jersey cost $250. The only backing for my strut inside the hull was a couple of thin 5/16 stainless fender washers. The fiberglass build-up for the strut here is about 1/2". The fasteners were 5/16" flat Phillips head screws run up into the boat from the outside through countersunk holes in the bronze strut. The strut was set into some sort of hard material to provide alignment during final assembly. It never leaked, but I never really cared for the arrangement either. What with the screws being bent and set into some sort of hard bedding it was near impossible to get them out. I of course have decided to mount the new strut a little differently. I made up a plate for inside the hull out of 1/4" aluminum plate I had lying around. Drilled and tapped at the original hole centers for 1/2" diameter studs 3" long cut from a piece of stainless 18-8 threaded rod. The studs thread into the plate and are nutted above, locking them in place with Loc-tite or 5200. The plate with studs will be bedded into the hull with a thickened epoxy mix, keeping the epoxy off of the portion of thread exposed outside the hull. Once cured the strut will be put up onto the studs and pulled up into another bed of thickened epoxy and held in place with 1/2" self locking nuts. I expect to be able to remove the strut if necessary without disturbing the water tightness of the backing plate. ------->>> An aside here: Hunter's original installation of my stern tube was off a bit. It is angled downward slightly from what it should be so that if I line up the stern tube, shaft and strut properly the strut will sit about 3/4" from the hull and the engine has to sit up a bit higher than it should. (Think see-saw with the stern tube as fulcrum.) This angle in effect reduces the clearance through the stern tube and is a major contributor to the shaft banging the tube under certain conditions. At this point I have no interest in resetting the stern tube so I think I'm just going to split the difference. My only concerns are: The choice of epoxy as the bedding material. It is real permanent and I'm screwed if I change my mind. That area at the back of the hull is not a fun place to work. I'm open to suggestions on this one. A little well will be formed by the plate and bedding which will tend to hold water. I'm figuring on just filling the area with foam. I'm open to thoughts on this one also. I'll just live with the miniscule amount of drag added by having the nuts on the outside. samlust@monmouth.com
 
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Fred Moore

how about bolts

You might consider using stainless bolts from below, and bedding the plate with 5200. It would not be as permanent as epoxy, but 5200 will keep the plate from moving when you take it loose, just a thought.. Fred
 
H

Howard

Backing Plate- You betcha !!

Fiberglass is a funny thing. When a vibrating object is afffixed to the glass, the heads of the screws or rivits tend to act like little knives. Ask any owner of an old Corvette. The glass panels vibrate and eventually break loose where the are affixed to the metal frame. Anyway on my 1978 H-27 the strut was backed by a marine plywood plate. Last year I relaced it with 3/4" oak covered with a rot perventer. I held it in place with 5200 and drilled the holes from the outside. Then I bedded new stainless screws with 5200. On the inside I put large SS washers with lock washers & nuts. Then for good measure I added avation nuts (SS with a nylon insert.) An aluminum plate would work as well but is a lot harder to work with. I did this after a line got causht in my prop wich un seated the strut (the old plywood was a little mushey).
 
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Pat McCartin

Aluminum is a good idea but...

Has anyone else considered or used some of the "machineable" plastics on the market ie..Delrin, HDPE ? Pat McCartin 1979 H30 "Therapy" Lake Lanier, GA
 
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