Reinforce Stanchion Bases with glassed in Knee's?

[Cool Beans]

I'm sure I'm not the only one who is/has experienced this before. At my lifeline stanchion bases, when you put any amount of force on them, the deck flexes Assuming the core was punky, I repaired the area and it still flexes (the core was wet, but not rotten) :cry:

The core and liner stop about an inch from the edge of the outer deck. From the edge of the core, it is just the 1/4" thick outer layer of glass, then turns up for 2 inches, and then over to sit on the lip of the hull.

When you push or pull on the stanchion, the deck pushes down and bends the deck at the core/glass transition and rolls the deck flange down. It does this at all the stanchions, and pulpits. The gelcoat is cracked at these areas as well, for the length of the flex.

My question is, how can these areas be reinforced? I know I can glass in some wood knee's to support the deck that would be strong enough. My concern is, am I creating a hard spot that will cause me further headaches down the road? Are these boats supposed to be "flexy"? Any other alternatives?

Thanks!!

 

[zeehag]

do they have backing plates or merely washers backing them?

 

[sailaway78]

Backing plates

Backing plates are the easy answer to this. If you can get to them from the inside. Find you some scrap aluminum plate, and put the biggest pieces you can squeeze under there.

 

[tommays]

Getting the station base load spread over enough surface area goes a LONG way

 

[RAD]

Your Ranger and my 32 Oday came from the same family and mine had these weeny washers and although I removed the wet core and injected epoxy and hefty backing plates my deck flex's too....don't get me wrong I did improve the situation 125%
Here's a picture of my SS backing plates that I fabricated from scraps found at my friends metal shop and how I accessed the stanchion bolt nuts from the interior liner that left now way for maintenance

 

[Cool Beans]

Appreciate all the pics and advice!! There are backing plates, and they are easy to access. . .I will have to make new ones though, the originals are thin and bent. . .

I like the idea of sitting the stanchion on a larger plate. That might help with the deck creasing at the edge of the core. Instead of a SS plate, Would fairing in a piece of 1/4" G-10 suffice? Then I can paint it and make it look pretty

Also, in general, is it bad practice to "reinforce" these old classic plastic boats? All the bulk heads sit on the fiberglass liner, but nothing supports the liner. 36 years and it is sagging a bit and springy. I wouldn't mind jacking everything back up tight and glassing some 1/2" plywood from the bottom of the liner to the hull. Would the Knee's be a bad idea? Everything is easy to get too. . .

Thanks!

 

[mitiempo]

Backing plates larger than the stanchion base are a good idea. G10 plates epoxied to the deck underside would be a better choice as they would actually strengthen the area under the stanchions instead of a plate that is not a pert of the deck. I would probably use thicker than quarter inch if possible and place it with thickened epoxy between it and the deck.

 

[FastOlson]

Plus One on large backing plates

Backing plates larger than the stanchion base are a good idea. G10 plates epoxied to the deck underside would be a better choice as they would actually strengthen the area under the stanchions instead of a plate that is not a pert of the deck. I would probably use thicker than quarter inch if possible and place it with thickened epoxy between it and the deck.

When I pulled and reinforced all of our stanchions, I put large G10 plates underneath each one. I used mostly 1/4 or 3/8 G10, set in epoxy mush. I also braced all of the midships stanchions to the rail and two-way braced the gate stanchion on each side.
Easily the most rewarding upgrade we've done in 15 years of ownership.

If you email me back channel, I can provide a link to the project. It's over on the Ericsonyachts.com site.

LB

 

[Ross]

Re: Plus One on large backing plates

All of the advise given has suggested that you distribute the stress over a larger area. This is valid. This is what you will be doing if you choose to reinforce the area around the stanchion bases. I reinforced the deck of my boat but I don't recommend that approach to very many people because it is an awful lot of very messy work.

 

[mitiempo]

Most of the force on a stanchion is from it being pulled outwards from the top. If the reinforcement is both fore and aft of the stanchion base and inboard a ways as well it is just about all you can do. The outboard side doesn't usually give you any room for strengthening on that side anyway. The biggest problem is access with cabinets and liners in the way.

 

[RON20406]

Coolbeans, Two additional comments: 1.) The G10 is a great idea to spread the load and make a monocoque construction when "cemented" with thickened epoxy as long as there is no delamination in the core and 2.) The other advantage of the G10 is that it slightly raises the stanchion base for potentially less egress of water at its terminal points. Before painting, round off the edges of the G10 to prevent accidental toe stubbing. Good luck and good sailing, Ron

 

[mitiempo]

Generally the reinforcement, G10 or otherwise, is installed inside the boat and not outside under the stanchion. Properly sealed there should not be a leak - especially if there is not any flex.

 

[RON20406]

Generally the reinforcement, G10 or otherwise, is installed inside the boat and not outside under the stanchion. Properly sealed there should not be a leak - especially if there is not any flex.

An 1/8" to 3/16" aluminum or stainless backing plate is far superior to G10 underneath the installation. The purpose of the G10 above deck further spreads the loads, prevents excessive stress fractures and elevates the stanchion base slightly above the deck. I also use a 1/8" to 3/16" piece of plumbers gasket under the stanchion base with ample sealant to allow for flexing. This is as close to monocoque construction as possible for this type of installation. Good luck and good sailing, Ron

 

[mitiempo]

On a lot of sailboats the stanchions are tied in with and overlap the aluminum toerail and there is not any way of adding G10 topside.

The plumbers gasket will not move with flex like a good sealant (butyl, Sika Flex 291, or 4200) that has good elongation will. Many Pearsons have problems and wet core because of this as they used rubber gaskets under the stanchions originally.

 

[RON20406]

On a lot of sailboats the stanchions are tied in with and overlap the aluminum toerail and there is not any way of adding G10 topside.

The plumbers gasket will not move with flex like a good sealant (butyl, Sika Flex 291, or 4200) that has good elongation will. Many Pearsons have problems and wet core because of this as they used rubber gaskets under the stanchions originally.

Mitiempo,
A rubber gasket will yield more than a hardened sealant since the sealant, once cured/compressed, can no longer expand beyond its hardened form under a load. My boat is a Pearson that is 21 years old and still has two original stanchion gaskets forward of the mast that have not leaked nor is there any moisture in the core. The secret to stanchion maintenance is to check the torque of the bolts on a yearly basis and look for any compression issues that may have occured to the fiberglass substrata indicating core fatigue/failure. The concept of a gasket is sound engineering, but like many things on a boat requires attention. In re: stanchions tied in with a toerail, you are absoultely correct that G10 could not be used above, but in that case, a proper aluiminum/stainless steel backing plate to spread the load would be superior to the G10. Good luck and good sailing, Ron

 

[mitiempo]

Ron

Good sealant doesn't harden - butyl being the ideal - and can always expand and stretch as required. The butyl on my CS27 still is as flexible and sticky as when it was installed in 1977. The hardware on Maine Sail's CS36T was bedded with the same butyl by the CS factory during construction. It doesn't harden with age. The only fittings I have had a seal problem with are those a previous owner added. When I removed my forehatch because of leaks between the lens and frame as well as general old age the hatch/deck seal was perfect and the butyl was still as stretchy and sticky as installed originally.

A good builder at taking care of details would not place stanchion bolts through a cored section of deck - CS stanchions are bolted outboard of the core section of the deck as they should be. If there is a core in the way it should be replaced with either solid layup or removed and replaced with thickened resin - epoxy now and polyester in the past. In other words core failure shouldn't be an issue because core should not be there.

Due to the gasket's lack of stretch and lack of adhesion to both the deck and stanchion base it is poor engineering in this case and in the case of any other deck hardware that can move under load.

If you have only 2 stanchions that are still using gaskets still why did you not replace the others with gaskets if they are so good for this purpose?

I fail to see why a backing plate that is not permanently attached to the deck as in aluminum/stainless would be better than a backing plate that is permanently attached as in G10/thickened epoxy.

Respectfully

Brian

 

[Solace of Freedom]

striped stanchion screws

I don't want to get in the middle of this 'heated' debate, but mitiempo certainly seems to know what he is talking on. I had to remove a broken stanchion a few years ago. I could access the inner bolts' nuts but the outers are only screws (the whole cabin interior is one big liner). Now, the screws are striped, and I have a leak. Would it be better to epoxy the screws in or epoxy over the holes, re-drill, & screw them in? Or, what might be another solution?

 

[RON20406]

Ron

Good sealant doesn't harden - butyl being the ideal - and can always expand and stretch as required. The butyl on my CS27 still is as flexible and sticky as when it was installed in 1977. The hardware on Maine Sail's CS36T was bedded with the same butyl by the CS factory during construction. It doesn't harden with age. The only fittings I have had a seal problem with are those a previous owner added. When I removed my forehatch because of leaks between the lens and frame as well as general old age the hatch/deck seal was perfect and the butyl was still as stretchy and sticky as installed originally.

A good builder at taking care of details would not place stanchion bolts through a cored section of deck - CS stanchions are bolted outboard of the core section of the deck as they should be. If there is a core in the way it should be replaced with either solid layup or removed and replaced with thickened resin - epoxy now and polyester in the past. In other words core failure shouldn't be an issue because core should not be there.

Due to the gasket's lack of stretch and lack of adhesion to both the deck and stanchion base it is poor engineering in this case and in the case of any other deck hardware that can move under load.

If you have only 2 stanchions that are still using gaskets still why did you not replace the others with gaskets if they are so good for this purpose?

I fail to see why a backing plate that is not permanently attached to the deck as in aluminum/stainless would be better than a backing plate that is permanently attached as in G10/thickened epoxy.

Respectfully

Brian[/quote


Mitiempo, I will not again get into the butyl/sealant/gasket debate since that has been addressed ad nauseum over countless blogs and is not needed here, but I would like to address three issues: 1.) It defies the law of physics that a rubber gasket lacks stretch. The adhesion of a rubber gasket is accomplished by a bedding compound of your choice, 2.) The reason I have replaced all but two of my gaskets is that my boat is 21 years old and I believe that very few materials last a lifetime, so without a paranoid necessity, I have replaced a few a year over the last several years. I think this is just prudent maintenance for a well found boat and 3.)the difference between a stainless/aluminum backing plate vs. G10 is that a metal plate will not flex, distort or develop stress cracks like the more forgiving fiberglass/G10 which is why it is always preferable on a well found yacht. Finally, the purpose of this discussion is not to proselytize over what you or I think is the best way to do something, but rather to allow our more analytical readers to know there is more than one way to accomplish a quality installation based upon one's particular needs and desires. I believe that writers in these discussions have a responsibility to those who are new to sailing and sailboat maintenance to showcase techniques that have proven successful in real life conditions over the long term. My system has worked for me as yours has apparently worked for you. Let the readers decide which system they like best. This is not a contest for Prom King. Good luck and good sailing, Ron

 

[mitiempo]

Ideally the liner can be removed so bolts can be used to replace the screws. The section can be covered after it is done.

It is unfortunate that builders of boats (in all price ranges) bury hardware attachments that will need to be accessed later. With people grabbing stanchions to hold the boat off the dock or get aboard screws are a guarantee of failure eventually.

The other possibility if that is not possible is to use a toggle bolt. While not as good as a bolt with nut it is much better than a screw. It will require a larger hole and if the stanchion base is large enough to cover the hole size required while still leaving enough of the base to get a good seal it should work.

 

[mitiempo]

Ron

The leaks and wet core caused by Pearson's rubber gasket installation are well known. While I think a good sealant like 4200 is a better choice and is time proven butyl is better yet as is countersinking the holes to create an "0" ring of sealant where it is needed most.

While you are set in your ways others may want to see this link for a great method that doesn't fail. http://www.pbase.com/mainecruising/rebedding_hardware

As far as backing plates, as long as there is enough room a G10 or even fiberglass plate that is larger than the stanchion base and epoxied in properly will virtually eliminate the flex that causes the problem. Thick fender washers should also be used.