Mainship 34T Stanchion backing plates

daviddraper · 01-05-2018, 05:57 PM

I have an accepted offer in on a 2006 34T, but have not yet finalized the deal.
The boat has a few stanchion issues, such as one of four stanchion bolts appearing to be stripped on a number of the stanchions, and most of the aft flybridge stanchions are loose.

Does anyone know what is backing the machine bolts that are used for the stanchions? I can't see how I would gain access to the backing plates or nut/washers (whatever is used). Any ideas? Would I have to cut access panels below each stanchion in the gunnel side?

If I buy the boat, this will have to be addressed asap to avoid any additional water intrusion.

DavidM · 01-05-2018, 06:34 PM

I believe but am not absolutely sure that each stanchion base has an aluminum plate embedded in the fiberglass underneath with threads for the stanchion bolts. If yours are stripped then replace the bolts with a size larger and tap the plate for the larger size. Make sure that you bed the base with 5200 for strength and a water seal around the holes.

David

LongJohn · 01-05-2018, 06:39 PM

On my 2005 34T, all of the handrail stanchions are simply screwed into the fiberglass. The lower end of those posts that support the aft flybridge area are also screwed into the fiberglass. The only attachments that I have found to have a backing plate are cleats.

**Bacchus** · 01-06-2018, 06:41 AM

I can confirm that the undermount swim ladder on our '08 MS 34HT has alum plates bedded in the FRP.
Have always wondered about rail stantions?
Also... I'd recommend considering butyl tape for sealant and lookinh through the Compass Marine How To re rebedding deck hdwre.

https://www.google.com/url?sa=t&sour...QfY2olF0flBb3W

Great info. I've used CM butyl and it is good stuff... better than the local RV supply place had.

Don
'08 MS 34HT
"Bacchus"

daviddraper · 01-06-2018, 11:30 AM

Hopefully tapping embedded plates is all I'll need to do, along with as mentioned, re-sealing. Thanks!

**Bacchus** · 01-06-2018, 02:22 PM

If you find the bolts are only threaded into plywood / FRP you might consider epoxy to rebuild any stripped out holes. A little tricky w/ through holes as epoxy will tend to run out but you should be able to at least partially contain the run out w/ a small piece of cloth / tape or cotton ball tied on a string / wire and inserted through the hole and pulled up snug to the bottom.

Please report back as to what you find when you get into it - I have always wondered but haven't had the need to tackle my rail stanchions so far.

Symphony · 01-07-2018, 01:59 PM

All boats, even new boats (especially new boats) come with bodges and problems.

take a few pictures when you pull up a stanchion for repair. I wonder if all of them have embedded backing plate?

PS I wouldn't use 5200 as a sealant on anything that might need to be dissambled in the future, or more likely, did now sit right after the repair. Butyl tape, or 4200 would be better.

Good luck and enjoy the new boat.

**Shrew** · 01-08-2018, 09:01 AM

My 350 (applies to the 390 as well), have plates in the fiberglass. I'm fairly sure they are aluminum. They're drilled and tapped and act as both the nut and backing plate. I did some handrail work this past summer.

When you re-caulk, make sure to use something UV resistant, such as 3M 4000. (4200 is NOT UV protected, and 5200 is not the appropriate product for bedding deck hardware).

Dougcole · 01-08-2018, 08:34 PM

On a related note, one of the screw heads on the base of one of the supports for the aft upper deck sheared off on my 400T. The screw is corroded and below the level of the base.

Any idea how I can get it out?

jleonard · 01-09-2018, 07:15 AM

Drill it out and re-tap or helicoil.

jskinner30PII · 01-09-2018, 01:53 PM

Why would they use aluminum backing plates if the screws arestainless? Dissimilar metals? Cheaper? Id be interested in what you find out.

jleonard · 01-09-2018, 04:19 PM

Quote:

PS I wouldn't use 5200 as a sealant on anything that might need to be dissambled in the future, or more likely, did now sit right after the repair.

FYI 5200 is easy to remove. I never had any problem and that's mostly what I use. A little heat to break it down and/or a sharpened thin putty knife will cut right thru it.

Quote:

Why would they use aluminum backing plates if the screws are stainless? Dissimilar metals? Cheaper?

It's Mainship. I had an original 1978 Mainship and they didn't use any backing plates. Not even fender washers. At least they progressed but they probably "downsized" their metallurgist.

daviddraper · 01-10-2018, 04:28 PM

Thanks everyone. Once I have the boat here (I'll be running it down from Maryland to Florida in early June), I will post all the work I do as I progress through all the deficiencies. I'll be able to figure out pretty quick whether there is an embedded backing plate. Based on the fact that the stripped stanchion bolts are in a fact machine bolts and not a screw sorta points that way.

I got a good price on the boat, so hopefully I come out ahead after lots of DIY work. Mostly the boat has pretty good bones and should shine up pretty good :-)