Hunter 170 Rudder Mount Solution

Slider · Aug 12, 2015

Ruder Bracket

SAILOR IKE said:
Over the last three years, I have been trying to repair the rudder mount on my 170. I have followed several solutions in this form and other sources to resolve this issue. These solutions have failed to keep the rudder bracket firmly on to the rudder mount when the winds are moderate to high. The last time the rudder bracket pulled away from the rudder mount, I noticed there was a tremendous amount of flex in the back plate of the rudder bracket. Since the tabs on the rudder bracket are of two different lengths, the top mounting screws take most of the force because the flex in the rudder bracket. After thinking about the problem, I believed that the problem does not lie with the rudder mount but with the rudder bracket. During the winter I spent quite a bit of time talking about the rudder bracket with my sailing buddies and I bounced a few ideas on how to eliminate the flex in the rudder bracket. I believe the rudder bracket is made of 1/8th inch stainless steel and thought that doubling the thickness of the back plate of the rudder bracket would eliminate or significantly reduce the flex in the rudder bracket. I took the rudder bracket to a welder who specialized in stainless steel welding and asked him to add another 1/8th inch stainless steel plate onto the back plate of the rudder bracket. I asked him to be sure to weld around the circumference of the bracket to ensure that the additional plate would be firmly attached to the back plate of the rudder bracket.

On my vacation in August, I installed the modified rudder bracket to my 170. I filled the old screw holes in the rudder mount with epoxy and added four more screw holes in the rudder bracket giving the bracket 10 screws to hold the bracket to the mount. (This might be more screws than I needed but after the wear and tear on the rudder mount screw holes from the flexing of the rudder bracket, I wanted to be sure that the rudder bracket did not fail because of this wear and tear.) We got 14 sails on the lake in August with three or four with the winds in the moderate to high range. My preliminary assessment of the modified rudder bracket appears to be a complete success. I felt the rudder to be firm with no flexing. A much more positive feel in the tiller which I haven’t seen in the past three years.

Although I am not an engineer and this solution appears to be common sense, I hope that this solution to this problem will work on your 170. I would be interested in finding out the successes in applying this solution to the rudder mount problem.
Best regards

Mike

Mike, you are correct! The 1/8 SS is not strong enough to take the twist on the rudder bracket. The last few sails, I could see movement at the top of the bracket which worked the top 2 screws loose. I just had a shop make a new bracket with 1/4 inch SS. There is no way the new bracket will bend or flex. I also, will add 2 more screws two the mount. I will fill the holes before remounting the bracket. It is a smart move to fix this problem before there is major damage.

mark2 · Aug 13, 2015

We completed a major repair of our rudder bracket and the rudder mount this winter. Symptoms were the same as you noted - twisting in the bracket and pulling the top screws lose. In addition, the top screws would not tighten and felt soft. When I removed the bracket it was clear that a prior owner had filled and redrilled the holes once already.

Our solution was a bit more drastic. After consulting with 'Crazy Dave' we drilled a 3" access hole in the side of the rudder mount so we could get to the backside of the mounting area. We found the plywood embedded in the foam was wet, mushy, and delaminated (later we found a leak at the waterline below the rudder where the top and bottom halves of the hull are joined. The entire interior of the hull was wet and probably had been for a long time).

Besides fixing the leak to prevent moisture, we decided to use stainless steel bolts rather than screws, and to use a back plate inside the hull to secure the bracket. We also had a welder add "gussets" along both sides to strengthen and stiffen the bracket. (Make sure you find a welder that knows how to work with stainless steel, not all of them do).

It was a bit tricky because we found the top bolt does not project into the cavity, it ends in the foam layer near the top of the hump. We had to cut away some of the interior fiberglass and foam to fit in the back plate, like this:

We were concerned about creating a weak spot where we cut away the fiberglass layer, so before mounting the bracket we laid in a layer of fiberglass embedded with Devcon plastic welder. Here are some photos of the exterior after all the repairs, and some interior pics of the bolts and back-plates.

The upper bolts were hard to install - very tight working space:

We will cover the 3" hole with an access plate cover so it will continue to provide access to the hull interior (great for leak/dampness inspection). In another post I'll describe how we took photos/movies of the entire interior of the hull to look for damage.

Notice we removed a section of rub rail below the rudder so we could repair cracks behind the rub rail. Both the upper and lower hull parts were cracked in the corner behind the rail. We removed the rail section, cleaned up the cracks, and covered with several layers of fiberglass and Devcon joining the upper and lower hulls. Also applied some fiberglass and Devcon to the inside of those areas (another good use of the access hole).

We have sailed several times so far this year with the repaired rudder system. It it rock solid in the most challenging wind, and as someone else observed, the rudder feels so much more responsive than before. We were very nervous about this much invasive and structural work, but it turned out very well.

--Mark

Jackdaw · Aug 13, 2015

Nice mod! You should work for Hunter Engineering. They clearly need the help!

Every time a see a structural SCREW on a sailboat I want to back it out and throw it at the clown who approved its use.

You did the right thing by removing material and adding bolts to the top of the strip. I would not worry much about that area being weakened.. I’m sure it was in an absolute sense, but the inherent three-dimensional nature of the area in question adds a lot of strength. Nice work.

behrmann56 · Aug 13, 2015

What if you just plugged the holes and predrilled and re-inserted the screws and added the extra screws like you did and then just coat the whole backside of the bracket completely with Plexus? I just had the same problem with the 2 top and bottom screws pulling out and will not retighten.

Slider · Aug 13, 2015

Great Diagram

mark2 said:
We completed a major repair of our rudder bracket and the rudder mount this winter. Symptoms were the same as you noted - twisting in the bracket and pulling the top screws lose. In addition, the top screws would not tighten and felt soft. When I removed the bracket it was clear that a prior owner had filled and redrilled the holes once already.

Our solution was a bit more drastic. After consulting with 'Crazy Dave' we drilled a 3" access hole in the side of the rudder mount so we could get to the backside of the mounting area. We found the plywood embedded in the foam was wet, mushy, and delaminated (later we found a leak at the waterline below the rudder where the top and bottom halves of the hull are joined. The entire interior of the hull was wet and probably had been for a long time).

Besides fixing the leak to prevent moisture, we decided to use stainless steel bolts rather than screws, and to use a back plate inside the hull to secure the bracket. We also had a welder add "gussets" along both sides to strengthen and stiffen the bracket. (Make sure you find a welder that knows how to work with stainless steel, not all of them do).

It was a bit tricky because we found the top bolt does not project into the cavity, it ends in the foam layer near the top of the hump. We had to cut away some of the interior fiberglass and foam to fit in the back plate, like this:

We were concerned about creating a weak spot where we cut away the fiberglass layer, so before mounting the bracket we laid in a layer of fiberglass embedded with Devcon plastic welder. Here are some photos of the exterior after all the repairs, and some interior pics of the bolts and back-plates.

The upper bolts were hard to install - very tight working space:

We will cover the 3" hole with an access plate cover so it will continue to provide access to the hull interior (great for leak/dampness inspection). In another post I'll describe how we took photos/movies of the entire interior of the hull to look for damage.

Notice we removed a section of rub rail below the rudder so we could repair cracks behind the rub rail. Both the upper and lower hull parts were cracked in the corner behind the rail. We removed the rail section, cleaned up the cracks, and covered with several layers of fiberglass and Devcon joining the upper and lower hulls. Also applied some fiberglass and Devcon to the inside of those areas (another good use of the access hole).

We have sailed several times so far this year with the repaired rudder system. It it rock solid in the most challenging wind, and as someone else observed, the rudder feels so much more responsive than before. We were very nervous about this much invasive and structural work, but it turned out very well.

--Mark

Great Job. I have been very interested to know what the inside of the rudder block looked like. The Bolts makes it a strong solution. The next question is, will the block take the stress?

Thanks , Richard

mark2 · Aug 14, 2015

Slider said:
Great Job. I have been very interested to know what the inside of the rudder block looked like. The Bolts makes it a strong solution. The next question is, will the block take the stress?

Thanks , Richard

I worried about weakening the entire rudder block, but as someone else mentioned it's 3D triangular shape gives it a lot of strength. The hole is in the side which I think does not carry much of the stress - I am not a mechanical engineer but I think the main stress lines are in the corners. It seems rock solid so far in 15-20mph winds.

Here is another photo of the inside of the block that was in the prior post but did not seem to appear. The white material is new Devcon used to strengthen the upper section where we had to cut through the fiberglass.

The hump is made the same as the rest of the boat - a hollow core made from plastic skin over 2-3" foam over a layer of fiberglass. The cavity is not large due to the thickness of the foam.

Having that access allowed me to inspect the entire interior of the boat. I made a sled for my iPhone and tied a string on each end. I ran one string through a forward cup holder (removed), and the other through the hole in the rudder mount. I turned on the flashlight function and video recorder, and pulled the phone from the stern to the front, getting a view of the underside of the upper part of the hull. I will post that video when I can. Here is a video just from holding the phone inside the cup holder for a look around at the interior of the forward part of the boat:

https://www.youtube.com/watch?v=7FegO5UjVlI

Crazy Dave Condon · Aug 19, 2015

The biggest problem here was wood screws holding the rudder bracket in place screwed into wood. When wood gets wet, big problem and you have to go to plan B. That is to cut for a three inch inspection port, let the area dry out, fix the leaks normally from the wood screw area and sometimes the rub rail, and use backing plates to secure the rudder bracket. I concur adding additional thickness to the bracket but never did with the repairs for this made in my years as a dealer but did work. I did add two additional bolts in the center.

Forget about filling the holes and reusing that as the wood is shot once it got wet.

Sternstern · Apr 14, 2019

Do you know of a professional who can do this project (rudder bracket and repair from inside rudder housing via a 3” inspection port? (Southeast US)?

JimInPB · May 8, 2019

I did a similar repair, except that my wood wasn't rotted, so I just drilled out 1/2" or 5/8" (I forget which ) holes & filled them with epoxy soaked rolls of alternating chop strand & roving. When it hardened up, I filed the plugs flush, drilled out pilot holes & put screws back in. It's been that way for many months now with no problems. Screws are OK as long as you have enough diameters of engagement in a good solid base material. I did a write up on it with pictures somewhere. I think it was under Hunter small boats, but I forget.

Edit:
I found my write up from back in June of 2018. Unfortunately, no pictures - https://forums.sailboatowners.com/index.php?threads/h212-gudgeon-repair.191936/

This was done on my 212, which is basically a larger brother to the 170.

Shorefun · May 10, 2019

My motor mount wood was not in very good shape. The screws would not hold. Before I did the major cut operation others have done I decided to try a less invasive method.
I found that I could use a long pointed scribe and push in at an angle into the wood and get some resistance. So something was there.

I got the real thin epoxy called Git Rot. It is like $30 for 4oz or $16 online. I drilled smaller holes around the areas and proceeded to put in the epoxy or first pack in some wood dust from my miter saw and add in the epoxy.
The epoxy takes a few days to cure depending on temp. I was doing some in 50 degree temps so I also put a 100 watt light on the area to keep it warm.
After like 4 or 5 fill let cure open new holes and probe and put more in I got it so the screws hold very tight. I figure through the season I will check them. I figure the worse that happens is I have to do the major cut operation.

Oh and I did fill the hole with the MA300 (it will be a small area you can get the Devcon packaged stuff at the local hardware store).

The Git rot I mixed with a tablespoon and 1/4 tablespoon stainless measuring set I bought ages ago to be able mix up small amounts of paints. I bought some plastic syringes and drilled the holes so the nose of the syringe fits tight.

I am sure there are many ways to skin the cat here. Do what you feel comfortable with doing.

BobbyFunn · Jun 1, 2019

When i bought my 2004 170 the rudder was loose, so fixed that right away. The screws werent grabbing so i flooded each screw hole with marinetex.

4 years later...the rudder is still very tight, however, the top two screw hole have cracks radiating out from them. since the boat is in the garage and is summer, its time to take care of this.

I studied this thread and was pretty sure i was going to do the same thing, then fix the cracks.

Let me tell you...These repairs are all wrong. Ill show you the complete rudder mount dissection so you dont make the same mistake.

If your rudder is loose and the screws are not grabbing anymore its because all the wood in the mount had turned to mulch. It cannot be saved.

I started this repair by drilling a 4 inch core from the top. The luran adhesion was excellent and the foam was thick and in good health. The top two screw hole areas were in bad shape. Spongy wet wood.

Running along the back, and exposed in the open hull space was a flaky mess of triangle shaped wood. I simply grabbed it with my hands and pulled it off the FRP.

I then got to the luran side and began using a screwdriver to dig out the wet mulch. There is another triangular piece of wood that is epoxied to the luran and sandwiched in the foam. None of it was dry. I got some on my garage floor and it smeared like dog crap when stepped on.

Initially, I thought the best plan was to just drill the top out and clear the trash out, but then realized that i would have to ruin most of the FRP and foam. It would be very hard to layup new cloth and foam. The new plan was to treat this like a regular cored deck and actually cut a little bit of the luran out.

Before i removed the luran i reassembled the rudder gudgen so i could study the movement that caused the cracks. It was intetesting that even with the core gone and the wood dissolved the rudder was solidly attached at very tight.

At this point the only thing holding the rudder on was 6 wood screws on luran and my marinetex epoxy. The only wood removed at this point was the hull side "backer plate". By wiggling the top screws i couldsee the triradial crack bulge.

If when the rudder is loose one simply fills the hole with a solid filler you are effectivly giving depth to the luran, getting a better grip on the luran, and then more leverage on the luran to crack it.

I used a dremel to router out a flat triangle panel so i could access the mulch. I stayed away from the curves so that the structure remains intact. I was abke to get aal the wood out but only after cutting out my marinetex repairs and the rivet for the VIN and capacity plate.

The repair should actually be easy. JimInPB made the same repair for the motor mount and his repair will be a good guide. I will first repair the FRP in the hull, then work my way to the luran. When this is over the luran will just be a waterproof cover and a decoration. Never let hardware touch luran! Never let luran be a part of anything structural unless the force is compression and spread out over large distances.

Hunter216 · Jun 2, 2019

Bobbyfun
When you decide to repair something you don’t mess around!! Your certainly getting your moneys worth out of that 4 inch hole saw :beer:

It looks like the 170 is somewhat prone to water intrusion as the original plywood gets damaged/destroyed. I wonder if this “leak” is in a common area. When you are sailing does the rudder mount get submerged? Maybe the water gets in the damaged screw holes while sailing or perhaps rain gets in somewhere forward and the water simply sits at the stern and the wood eventually soaks it up and rots.

Although pretty dramatic it seems to me that pulling out the rotted wood is the right thing to do. Leaving a disintegrating layer in place would likely cause trouble down the road. Like Mike Holmes says it’s all about the structure

The OP and others beefed up the rudder mounting hardware which would also make sense to me as the upper horizontal part of the rudder mount is quite long, I guess to make the pintel (sp) holes vertically align. If you think of the bottom hole as the fulcrum the top hole is the one counteracting the sideways force on the rudder blade, lot of twist there!!

Are you thinking about modifying the hardware as well?

BobbyFunn · Jun 2, 2019

Hunter216 said:
Bobbyfun
When you decide to repair something you don’t mess around!! Your certainly getting your moneys worth out of that 4 inch hole saw

It looks like the 170 is somewhat prone to water intrusion as the original plywood gets damaged/destroyed. I wonder if this “leak” is in a common area. When you are sailing does the rudder mount get submerged? Maybe the water gets in the damaged screw holes while sailing or perhaps rain gets in somewhere forward and the water simply sits at the stern and the wood eventually soaks it up and rots.

Although pretty dramatic it seems to me that pulling out the rotted wood is the right thing to do. Leaving a disintegrating layer in place would likely cause trouble down the road. Like Mike Holmes says it’s all about the structure

The OP and others beefed up the rudder mounting hardware which would also make sense to me as the upper horizontal part of the rudder mount is quite long, I guess to make the pintel (sp) holes vertically align. If you think of the bottom hole as the fulcrum the top hole is the one counteracting the sideways force on the rudder blade, lot of twist there!!

Are you thinking about modifying the hardware as well?

The wooden backer in the hull was actually drier than the internal wood plate.

I can think of 11 places in just the rudder.

6 wood screws that are sealed with a thin rubber gasket.

4 rivets that hold the capacity plate and VIN plate

Thin FRP layup near the hull deck join.

Just washing the boat down will allow water by capillary action to soak the wood. It can never evaporate out.

If the maufacturing process skipped the wood and used more foam, and also used a G10 backer board in the hull space we wouldnt be having this issue.

If Hunter speced out an epoxy bedding all the way from the luran, through the core to the hull there wouldnt even be a need to water seal it.

Its hard not to name call and disrespect the Hunter design team. Im convinced Hunter assumed the boat would be recycled once the first set of sails blew out.

"If you dont have time to do it right the first time, when will you find the time to do it again."

Ill use the same harware. That part is fine with a good backer plate. The screws are going in the junk hardware box and replaced with nuts, bolts and washers. They will be torqued, then sealed back up with the 4" plug.

It would be good to use the new Hunter18 rudder gudgen as it has the central support to minimize bending. Ill see how much it cost to have one welded on

Hunter216 · Jun 2, 2019

Interesting article on the 18’s rudder. Doesn’t speak directly about the piece on the hull but it had to be stronger than the rudder.

https://wavetrain.net/2011/02/26/hunter-18-test-sail-with-dr-destructo/

Hunter216 · Jun 2, 2019

Hunter216 said:
Interesting article on the 18’s rudder. Doesn’t speak directly about the piece on the hull but it had to be stronger than the rudder.

https://wavetrain.net/2011/02/26/hunter-18-test-sail-with-dr-destructo/

Actually the cause of the rudder failure is explained in this article. It sounds like the same test sail but different write up. The rudder that failed is from a 170.

https://www.google.ca/amp/s/www.sailmagazine.com/.amp/boats/the-hunter-18

My point being it looks like Hunter figured out they had a good product idea with the day sailor line but dropped the Luran build and went with sturdier “traditional” construction for the “new”versions.

BobbyFunn · Jun 2, 2019

Hunter216 said:
Actually the cause of the rudder failure is explained in this article. It sounds like the same test sail but different write up. The rudder that failed is from a 170.

https://www.google.ca/amp/s/www.sailmagazine.com/.amp/boats/the-hunter-18

My point being it looks like Hunter figured out they had a good product idea with the day sailor line but dropped the Luran build and went with sturdier “traditional” construction for the “new”versions.

The new version is balsa core with FRP. Weighs twice as much. Guy sailing it seems reckless

JimInPB · Jun 2, 2019

A lot of boats out there have weak spots where water intrusion rots wooden internal supports or cores. It is becoming less common now that wood cores are largely being replaced by composites, but it still happens. Anywhere you see a screw in a deck, there should be a seal of some sort (like 5200). Anytime a fitting goes through a hull, the edges of the hold should be glassed in or at least sealed with 5200. I'll bet that if the original owner of a 170, were to pull out the gudgeon screws & 5200 them in, when the boat was new, the rot problem would be delayed by 5-10 years.

BobbyFunn · Jun 3, 2019

I think i have an idea to rebuild the rudder mount.

There are a couple project requirements:
* Rudder should stay on

* Rebuild is permanent
* No decay even with water intrusion

Need to perfect the first requirement.

Im thinking of creating a G10-foam core-FRP composite "transom" with the luran panel glued back on for looks.

Ill use the existing mount for the base of the transom. Before the luran panel is glued back on ill bed the 6 gudgen 4 rivet holes with epoxy to seal the core. There will be an additional smaller G10 backer plate on the FRP in the hull. Bolts will go through the gudgeon, luran, new core and then the backer plate.

Im not sure if i need a couple layers of FRP over the foam before I bond the G10 or if i can just pour foam between the G10 and the inner FRP layer. G10 is already FRP so thinking i can save a step. The Internal G10 layer would be adhered directly to the luran that is left on the mount.

Any issues you can think of?

my concern is the rudder ripping off, a floating away, while firmly attached to the luran panel, the core and the backer plate.

Hunter216 · Jun 3, 2019

BobbyFunn said:
Any issues you can think of?

my concern is the rudder ripping off, a floating away, while firmly attached to the luran panel, the core and the backer plate.

I have little doubt that you will NOT experience any failure or leaking in the "triangle" you are rebuilding but not having sailed a 170 I don't really know how much the rudder loads up so I can only offer my flimsy opinion.

The only potential failure I see is having the entire "triangle" tear out which I assume is what you mean by your comment of having your rudder float away :beer:

I've also never worked with G10 panels but assume there are very stiff so they wouldn't conform to any of the curves "inside" the triangle cutout area. If you intend to overlap several layers of glass and epoxy on the inside curve of the dome which is FRP already and then buildout your layers to the aft end then I can't see the tear out happening or if your sailing that hard then all bets are off anyway!!!

Hunter 170 Rudder Mount Solution

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