Rudder Post Failure?

Dan_Y

.
Oct 13, 2008
514
Hunter 36 Hampton
Our 2008 h36 had two cracks at that location but propagated radially out from the tube. The top of the tube is bonded to the deck/upper part of the boat from above and below when the upper part of the boat was bonded to the hull. You should be able to inspect the bond from the underside through the hatch in the aft berth. Hunter seemed to use a red epoxy on the tube and backing plate when bonding the top to the underside of the deck. The hull/deck seam is like 5200. The deck seems to be two layers of 1/4” frg with the cracks being in the upper layer. They were not visible in the lower layer when looking up from below deck, but somehow let water through. The cracks allowed water to leak down the outside of the tube, but not into the headliner. There is a plywood backing plate/donut that serves apparently as a flange to secure the tube to the underside of the deck. It started to delaminate from water intrusion. Why couldn’t they use G11???

Per Ken’s post above, moving the rudder did not open the cracks or allow the tube to move. The rudder shows no damage or signs of repairs, so I don’t think it hit anything. Rudder is solid while shaking. I brushed thinned epoxy to seal up the delaminated areas of the backing plate and then used 5200 to seal the cracks on the top side. That stopped the leaks and we have sailed about 600nm since then. Applying thickened epoxy and matting to ground out cracks is a better fix that I might do in the future. I need to RR the drag link bearings, which are highly rusted, and removing the horn(?) from the rudder post then would make the repair easier.

Maybe a year after we bought the boat in ‘15 from it’s first owner I removed the deck plate looking for a leak. The area around the tube, where yours is cracked, had been ground and heavily reinforced with more layers of glass matting. No gel coat had been applied over the additional frg. The radial cracks I have start a little ways from the tube, away from the reinforcement around the tube. The manufacturing procedures for the h35.5 show how the tube is bonded to the deck with about 12 strips of matting laid around the tube so the overlap and pass next to the tube. No aluminum or steel plate visible. The procedures are posted on this site somewhere and are highly instructive for h36 owners as well.

In 2015, when I found the cracks and reworked area, the dealer said that Hunter was reinforcing that area and had the work done on this boat at the dealer prior to selling the boat when it was new. Supposedly they forgot to do it at the factory. They layered up about 1/4 to 3/8” of glass matte around the tube. I don’t know enough about frg to know how stress stacks form or how serious they are.

The rudder bearings are probably just the high molecular weight plastic donuts top and bottom like in other hunters of the earlier era (‘90s). They were bonded in the tube with 4200 maybe and can be removed without much effort. I can’t remember at the moment if the tube is flared top and bottom to hold the bearings like my h30 had. I’ll look for some photos of the dealer rework and add to this post if I find them. Also, add more butyl to the hole where the engine controls and pedestal wires go below. That leaked more than the cracks and drained onto the very back of the headliner in the aft berth.
Dan
 
Last edited:
Jan 15, 2012
97
Ericson 28/2 Port Kent
This looks like an insufficient previous repair, doesn't it? Looks like someone just smeared gelcoat over previous damage.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
Hunter seemed to use a red epoxy on the tube and backing plate when bonding the top to the underside of the deck.
I doubt Hunter used epoxy anywhere on the boat, epoxy is too expensive. The red resin is probably polyester resin.

Glass mat would not be my choice for the repair, especially if using epoxy for a couple of reasons. First, most if not all glass mat is held together by a styrene based adhesive that dissolves in polyester and vinyl ester resin but not in epoxy. This leads to poor bonding with the epoxy and difficulty saturating the mat. Andy over on Boatworks Today did a demo on this recently (it may be on his Patreon page). Second, mat is not a structural glass. It's primary purpose in boat is to prevent print through from underlying layers of woven glass cloth. It provides a easily faired smooth surface. A second use to build bulk where strength is not the main concern and other cloth provides the strength.
 
Dec 28, 2015
1,837
Laser, Hunter H30 Cherubini Tacoma
Anything you smear into it will have to be removed (ground out) when/if you weld it up. If it won't be put on the hard any time soon I'd seal it up with a light sealant after taking a wire brush to the circumference of the fitting to see what is really going on. Epoxy, in my opinion, wont do much for you other than making the actual repair more difficult unless the whole thing shifts when turning the wheel which in that case it should be pulled.
 
Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA
I doubt Hunter used epoxy anywhere on the boat, epoxy is too expensive. The red resin is probably polyester resin.
I would expect that Hunter would indeed use epoxy rather than polyester to bond two things together. Polyester, compared to epoxy, makes an inferior mechanical bond between cured parts.

The red color could be from adding a filler (eg West 407 filler) or from using older hardener. Old hardener turns red, but that doesn’t impair its strength.
 
Last edited:

Dan_Y

.
Oct 13, 2008
514
Hunter 36 Hampton
So I guess I don’t know the difference between matte and cloth. I thought it was the same thing, the woven fiberglass material that you lay on in layers/plies. Using the the polystyrene resin makes sense. I just like the fact that the smell of epoxy is gone after it cures and the poly resin stinks for weeks or months.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
So I guess I don’t know the difference between matte and cloth.
Mat is random short pieces of glass stuck together with a styrene based glue. Cloth is woven like most fabrics. There are a confusing number of hybrids of cloth, matt and other kinds of glass fabric.

Here's a sampling of the various types of fiberglass available. Fiberglass Supplies
 

Dan_Y

.
Oct 13, 2008
514
Hunter 36 Hampton
Here is a photo of the dealer reinforcement with no gel coat applied.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
Here is a photo of the dealer reinforcement with no gel coat applied.
That looks to be epoxy, fresh epoxy with fresh hardener has a beige/yellow color. As @DrJudyB pointed out, old hardener has a reddish or mahogany color but is still effective.

Looking at the cloth, it appears to be a plain woven cloth. The light color lines running at right angles are the glass fibers. I won't opine on whether this particular kind and weight of cloth is the best choice, that is out of my knowledge base, however, it is more appropriate than mat.
 
Oct 29, 2016
1,915
Hunter 41 DS Port Huron
Don't know how much it will help but here is a start

You may find some interesting stuff here
 

Attachments

Last edited:
  • Like
Likes: JamesG161
Mar 20, 2016
594
Beneteau 351 WYC Whitby
I would not use gflex or 5200 ,you do not want any movement ,more movement could lead to total failure. I would mix up west with 404 filler which is high density structural gap filler and maximum strength . Once cured I would sand, then add matt first ,followed by bi axial cloth wider than diameter of casting 4 layers
 

CarlN

.
Jan 4, 2009
603
Ketch 55 Bristol, RI
I’d be surprised if that’s aluminum. Maybe a grey putty around the top inch of the upper rudder bearing or top of fiberglass rudder tube? Try taking a chisel to it and see if it breaks off like putty. If it is aluminum, epoxy won’t stick unless you can sand off all the oxide - which you can’t get to in the crack. If it is putty, chip it away and see what’s underneath it. Hopefully fiberglass laminate.
 
Last edited:
May 8, 2016
14
Hunter 36 Catawba Island, Ohio
Here's the response I received from Marlow-Hunter:

We do believe epoxy will adhere to plexus. To pursue this approach, you will likely need to break and clean up all plexus around the tube and seal the area with a thickened epoxy.
If we did this repair, we would feel more comfortable moving forward with fiberglass.
 
Feb 20, 2019
10
Hunter 28.5 Muskegon
The tube to hull joint most likely compromised as others have suggested.

Our hunter (28.5) was letting water in while underway (stern above water at dock). Found to have stress cracks at base of lower bushing area. Had to cut away the three bulkheads (soaked and rotted as well) to get access.

Bulkhead rot most likely during previous owner's scupper and exhaust hose leaks that looked to repeatedly fill aft bulkhead compartments based on stain marks. This may have weakened the bulkheads.
IMG_20200322_181808860.jpg
IMG_20200327_150759412.jpg
IMG_20200326_170824051.jpg
Screenshot_20200326-182111.png