I thought to update this thread with the details of what looks like to be a successful outcome to my “Pink Strut Blues” strut failure.
The narrative might be useful for other Cherubini 36 owners who ultimately will need to replace the strut. Some of the steps might apply for 37 owners who have the same strut (but different mounting configuration). Also I suspect maybe the 33's will have the same strut?
The Miller Island Propeller “Dahmer” H33 strut (as referenced in my earlier post) was delivered to the Berkeley Marine Center (BMC), my DIY haul-out yard, last Thursday. Kudos for the attentive customer service by Miller Island's Jackie and Rob!
Yes, it is the replacement part except for one exception, which with some discussion with Cree, BMC's manager, I was able to quickly and economically work around. Pictures are attached to illustrate the situation and remedies.
The exception is that I had noticed on the Miller Island spec sheet that their H33 model strut had propeller shaft angle 18 degrees. However, my rough estimate of my failed strut using my elementary school type protractor yielded more on the order of 22-24 degrees.
The difference was confirmed when I slid the new strut (which came with the cutlass bearing already installed) over the shaft and into position. The forward (engine) side of the new strut's base plate matched up exactly with my hull. But on the aft side, there was a gap between the hull and the base plate of maybe 1/8”+. Old and new strut side-by side are pictured below.
I asked Cree over and showed him that I needed to “fill the gap”. After a few moments look-see, he concurred that this was the best approach and I should bridge the gap with an item in stock at BMC's Chandelry ... A two-part product called Dyna-Glass (which is the marine equivalent of Bondo). With the addition of the catalyst, Dyna-Glass mixes initially into a thick paste. 10-15 minutes later, the compound becomes rigid and strong.
The next steps were:
- On the Cherubini 36, the inside strut mounting bolts/nuts are totally obstructed by sections of the interior liner. I cut out some of the liner to make the re-installation obstruction free. (Pictured.)
- To prevent the Dyna-Glass from sticking to the new strut's base plate, I covered the new strut's base-plate surface and wrapped over the edge with thin 3M type clear packing tape. Then I applied some PFT teflon boat wax for extra good measure to further prevent any chance of the Dyna-Glass from sticking.
- The new mating area of the hull bottom was thoroughly sanded and cleaned.
- I plugged up the bottom of the existing 3/8” strut-to-hull mounting holes with a tight wedge of masking tape so that the Dyna-Glass wouldn't be forced up into them during the next steps.
- I put the strut (with the the cutlass bearing already in it of course as above) onto the shaft. Using one of the yard's boat jack support stands which also had an articulating pad to press up, I “dry-fitted” the new strut to the hull so the prop shaft was perfectly centered. That is it looked just right and the shaft turned without any binding by hand. I took note of the exact location of the amount of press-up by the stand. Then backed off the stand. And slid off the strut from the shaft.
- Mixed up Dyna-Glass's catalyst with the Dyna-Glass paste. Quickly gooped on enough to cover the packing tape protected base-plate. Slid the strut onto the shaft and into position. Then pressed-up again with the jack stand exactly as I had noted in the dry-fit.
- Waited until the compound set-up. But before it become completely hard, I used a box-cutter knife to trim away the squeeze-out. Photo attached showing more Dyna-Glass on the aft side than on the forward side.
- I checked the alignment. Still good!
- From the inside, using an old 3/8” drill bit that I had dulled the sides with using a Dremel grinding fitting, and through the existing mounting holes in the hull, I started drilling down into the base-plate of the new strut. (Which is still pressed up onto the hull by the jack-stand from below.) Only about 1/8” or so. Then went outside again.
- Backed-off the pressure on the jack stand. Because of the packing tape and the wax, the new strut base-plate and the Dyna-Glass separated easily. I slid off the strut from the shaft.
- With the exact location of the 3/8” holes already made as above, I finished drilling through the base-plate. And on the strut side of the new strut's base, I needed to grind a flat face so the new bolts heads would match square. Note that since the new strut's manufactured angle was off by five about degrees from my need, then the new holes drilled through the base-plate need to be 85 degrees rather than 90.
- Another dry fit. All still ok.
- I beveled the new holes in the Dyna-Glass so that the bedding caulk/adhesive would be forced up and seal between the hull mounting holes and the bolts when tightened.
- The yard recommended SikaFlex caulk/adhesive as the final bonding compound. Since the strut is firmly secured to the hull with 3/8” bolts, something like 5200 is not needed.
- The new strut was firmly tightened to the hull. A helper on the outside should hold the bolt heads with a box wrench or socket so the bolts won't rotate when the nuts on the inside are torqued.
- I waited until the next day to cut-off flush the squeezed-out SikaFlex.
- I opted to electrically bond the new strut to the engine, so as to get anode protection from my shaft anode and my “fish anode”. I painted the strut first with several coats of non-conductive underwater primer. Then finished with the same bottom paint as the rest of the hull.
I expect that with grinding away and then more build-up of the hull attachment area with the appropriate product, the same basic process might work to attach a more "generic" replacement strut to a Cherubini Hunter 36. Such as:
http://catalog.buckalgonquin.com/item/sailboat-struts-2/bronze-sailboat-struts/mss4-125?
Might not be "racing caliber" aqua-dynamic, but otherwise functional? Old boat = be creative!
Just as aside, the first suggestion by my yard was "old boat" = custom solution = custom fiberglass/carbon fabricated strut + extensive hull area modification to make fit + alignment adjustments + "X " hours @ $95 = $2k-$3k. My Cost of $about $550 is a reasonable outcome. (Assuming it actually works in the long run!)
