Hunter 37C Prop Strut Replacement Question

[Rumbero]

I’m replacing the prop strut on my 1984 Hunter 37C. I have already secured the “H-34” replacement from Miller Island Marine, and I have a haulout date set for June 8. I ‘m going to use 3/8” bronze flat head bolts/nuts/washers to mount the new strut in the old location and need to order the fasteners because nobody seems to have them in stock locally.

Anyone know off hand the proper length of the bolts? It looks like it could be 4”-5” but I have no idea of assessing the length because the boat is still in the water. Your input is appreciated.

Thanks.

 

[Jim Legere]

From a long-ago memory of re-bedding the strut on my old 37C, 4 - 5" sounds right. I would go with 5" as the length has more to do with making the top of the thread reachable to spin the nut on, while draping yourself over the water heater. while trying to reach down through the 4" access hole, and trying not to drop the goddamn washers and nuts in the bilge...in short...boat yoga! My Hunter-supplied bolts were SS, not bronze. but I think the original prop shaft was bronze, not stainless. Go figure.

 

[Rumbero]

Thanks Jim. Luckily I removed the old water heater, manual bilge pump hose, and access panels from the quarterberth, so the access and yoga is not too bad for the nuts. I’d rather have the bolt lengths short enough to be able to get a long socket on them from above without bottoming out on the top of the bolt.

I’m also mounting a hydrovane to the transom, and that—especially the lowest H bracket—is going to require some level 5 boat yoga!

 

[Johnb]

Please take some pictures and follow up for those who may come after.

 

[shemandr]

The real challenge in replacing a strut is the alignment of the cutlass bearing, the stuffing box and the coupler. Be prepared to count washers and place them together as you dismantle. Or maybe you have access to tools and skills to re-align. But for me it wasn't a DIY job. Ouch$$$

 

[Jim Legere]

Here's how I did mine (to the best of my recollection - it was a couple of decades ago):

• Centre the shaft in the shaft log. The shaft log is pretty much the only nonadjustable part - It's really part of the hull. ( I used some small wood wedges to keep the shaft centred in the stern tube (shaft log).
• Slide on the strut, complete with a new cutlass bearing. Use washers, epoxy putty, or whatever is required to allow the strut to mate with the hull while keeping the shaft aligned in the stern tube.
• Attach the propeller.
• Install the shaft coupling on the prop shaft and proceed to align the engine to the shaft by conventional methods (adjusting engine mount, measuring with feeler gauges, etc.)
• Check the alignment again in the water.

If you do your own engine maintenance, this alignment should be owner-doable. If you hire a mechanic to change oil and filters, you will likely have to hire someone to do this too.

 

[Rumbero]

Thanks Jim and Andrew. I’m actually having a professional do this as it isn’t likely a job I’ll be repeating. I interviewed a few yards and was well satisfied that the yard I’m using knows what they are doing. They seem to think that—depending on the tenacity of the old mounting bolts and/or use of 5200—the exchange might be able to happen with the shaft left in bolted to the transmission. I’ll remove the max prop, and we’ll see how the old strut loosens up after removing the nuts and bolts. If it’s not cooperating, we may have to unbolt the coupling and press out the shaft. That part I don’t mind as much as putting the prop shaft back in utilizing an “interference fit”. On my boat there is precious little room between the transmission and PSS to tap that coupling back on the shaft. But if we have to go there—and something tells me we will—so be it.

I know engine alignment in the water will be needed after the new prop strut is in. Thanks for the steps/sequence to complete the project.

 

[Jim Legere]

I forgot to mention: if you need to pull the prop shaft on an H37C, you will first need to drop the rudder. Nothing is simple...