Keel Bolts question..

[boatman61]

Hi folks.. this is addressing a concern about keel bolts on a boat I am considering.. when I enquired about when the bolts were last checked I was told it was during the purchase survey in 2011.. and..
"A few of the keel plates were changed to stainless by the previous owner. Others are steel with some rusting but plenty of good metal that I have treated."
Now I may be totally wrong but for some reason in the back of my brain I am getting some bells ringing.. the keel is the standard iron fin keel found on Sadler yachts.
I really like the boat but have a long way to bring her as she's on the North Sea coast so soundness is a major consideration in getting to the Algarve.
Am I twitching for no reason or is a subconscious memory of basic metallurgy giving me reasonable cause..
Many thanks...

[MartinR]

"A few of the keel plates were changed to stainless by the previous owner. Others are steel with some rusting but plenty of good metal that I have treated."

I would have a look at it. Clearly a bell should be ringing. This sounds like they used dissimilar metals.

[boatman61]

My thoughts as well.. just hoping someone with 'expertise' in the subject will chime in with a high risk/low risk assessment.. the boat appears very well maintained otherwise and is lifted out of the water 6mths of the year.
She's a '77 model so 40years old.. or 20years afloat..

[chris95040]

My dumb question will reveal I do NOT possess the "expertise" you are looking for (but whattaya want, its the internet! )

But what do you mean when you say "keel plate"?

[boatman61]

Originally Posted by chris95040

My dumb question will reveal I do NOT possess the "expertise" you are looking for (but whattaya want, its the internet! )

But what do you mean when you say "keel plate"?

I presume the owner is saying that there's backing plates under the nuts that thread onto the top of the bolts.. provides a load spread as opposed to just the nut flush to the bottom of the bilges.. hull is solid glass.

[chris95040]

Originally Posted by boatman61

I presume the owner is saying that there's backing plates under the nuts that thread onto the top of the bolts.. provides a load spread as opposed to just the nut flush to the bottom of the bilges.. hull is solid glass.

Got it - yeah, my present boat its setup like that, with 4 inch square? half inch thick? bronze plates, bronze bolts.

I'd definitely want a peek at the bolt where it's been sitting in that plate. I'm no corrosion expert but steel looks way more anodic on the galvanic series than stainless steel, so I think your bolts would be slowly disappearing in that situation.

But no idea - if those assemblies are staying dry, not sure if there's a real problem, stainless and mild steel are mixed all over the place on my tractors.

[boatman61]

That's my concern.. the plates were replaced with stainless pre 2011 but how long before not known.. and bilges do get wet in the UK for one reason or the other.. not sure if the anchor locker drains into the bilge..
And I am pretty sure a keen seller will mop his bilges dry and clean before showing.. I know I do.. along with everything else.
Have experienced electrolysis in the past and it amazed me how fast it works so this possible galvanic action is a concern.
Have contacted a b/yard near there to see if I can get an inspection/replacement estimate.. may be the difference between buy or not if its a fortune.
Good news is its ashore on its purpose built cradle so no lifting etc involved.

[zeehag]

TRUST YOUR GUT. have a twitch it is for your survival.
check all. donot wanna read about our boaty being subjected to a fail keel affixment issue

[boatman61]

Originally Posted by zeehag

TRUST YOUR GUT. have a twitch it is for your survival.
check all. donot wanna read about our boaty being subjected to a fail keel affixment issue

Me neither.. Biscay's still pretty cold in April..

[MartinR]

Do you know if the bolts themselves are hot galvanized or stainless? Anyway, an inspection and maybe also torquing of the bolts should give a good indication.

[Jim Cate]

With the boat on the hard and an iron keel, shouldn't be too hard to withdraw one bolt for inspection, Phil. That's what I would surely do!

Jim

[Tricolor]

I would change the backing plates, can't be a lot of work as they're replaced not long ago. If you don't change them it will be a build in time bomb. Google for stainless steel bolts used in steel construction.

[boatman61]

Originally Posted by Jim Cate

With the boat on the hard and an iron keel, shouldn't be too hard to withdraw one bolt for inspection, Phil. That's what I would surely do!

Jim

Jim, I've contacted a b/yard in the area asking for an inspection quote.. if not too dear I will ask the owner if he'd mind me commissioning the job.
Don't really fancy the 1000 odd nm sail back home sweating all the way.. and she's just to nice to pass on by.
I'm in Portugal.. boats in the UK on the East coast.
Looks fine outside.. up snug and tight to the hull.. see if the yard gets back to me.. seem the biggest in the area.

[Jim Cate]

Sounds like a plan, Phil, and I hope it works out for you. Looks a nice and tidy boat from what I can see.

Jim

[pcmm]

In an iron keel, the bolts should be large galvanized cap screws. You should be able to unthread them for inspection one at a time. Replacement is easy. Beneteaus do this, they sell replacment bolt kits just for this. You should not be using stainless for this application hot dipped galvanized steel is closer electrically to the iron than the SS.