A Sail Away Offshore Cruising Boat For Less Than US$100,000—Decks, Hulls and SS Fittings

A classically fastened teak deck, in this case in fair condition.

[In Part 1 Colin provided general advice on how to decide if a refit of this magnitude is a path each of us should tread, and some preliminary things to settle before we even look for a boat.

So now that we have decided to focus on boats that have been well taken care of and not butchered by inept amateurs, we still need to be realistic about  potential flaws in materials and construction.

To that end, Colin turns his attention to seven construction areas where problems can turn a refit into a horror show we definitely don't want to star in.

Over to Colin.]

None of these problems might have caused any concerns in the early years of the boat’s life, but now (at say, 30-40 years of age) will all have to be rigorously inspected and, if necessary, repaired or replaced.

Many simply can’t be judged until in-depth examination has been carried out, but there are often tell-tale signs that can give you a fair idea of what you are up against.

Let’s take a look these areas in detail:

Colin, European Correspondent here at AAC, is a deeply experienced offshore sailor who holds a Yachtmaster licence, and a gifted photographer and talented writer who has added a whole new dimension to Attainable Adventure Cruising. In addition, since Colin and Louise are from England and had their OVNI 435, Pèlerin built in France, they bring a European perspective to our site. You can read more about Colin and Louise and their business at their website.

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Marc Jackson

Thanks for the hard won information and caveats, Colin. How often have you found a sailboat listing that gives any description of work performed on deck fittings, rebedding, etc? It seems be a very overlooked part of boat maintenance, yet very important to a boat’s assessment of condition in a sale.

John Harries

Hi Colin,

I couldn’t agree more. If it were me, I would be a lot more interested in the boat sitting in the corner of the marina that has never been anywhere, owned by the guy who just likes to putter on her, than the recent circumnavigator: https://www.morganscloud.com/2015/01/03/the-three-biggest-lies-yacht-brokers-tell/

Dick Stevenson

Hi Marc,
I have a paper maintenance log which covers all regular maintenance, large and small, and all projects/repairs etc. A friend/broker saw it at one time and commented offhand on how valuable these 15+ years of logs will be when we sell the boat. It is not why I devised this, but you are right to want to know history.
My best, Dick Stevenson, s/v Alchemy

Richard Elder

Hi Colin:
Great job of convincing any newby boat dreamer that he should never consider buying a used boat! LOL Reality is a bitch. But the other side of reality is that most new boats are so poorly designed for going to sea rather than partying in the BVI’s that they may be a worse choice that a mid-80.s boat that somebody has cared for. And cost three times as much and depreciate five times as fast!

And finally, perfection is the enemy of casting off from the dock. I’ve been around enough early Valiant 40’s (rented the same factory after they left the PNW) to consider them well built boats. Poorly designed hatches, stanchions semi-bedded over balsa core, inadequate insulation in the iceboxes, welded and undersized chainplates with a history of failure, lack of sufficient crown in the cabin top that makes the headroom feel constricted, and uncomfortable cockpit seating. To say nothing of the famous blisters that took the original company down. Yet many have circumnavigated and provided long term cruising homes. A great hull design like the V40 can make you forget the pimples and focus on the horizon instead of accumulating $800,000 for the perfect boat.

John Harries
Bill Attwood

Hi Colin
Great article which should save a lot of people both heartache and money. Corrosion of stainless chainplates where they pass through the deck has been covered elsewhere on AAC, but replacing them with new is neither difficult nor very expensive. Repairing any consequent water damage to the core not so. Another potential problem is where deck hatches with radiused corners have been fitted in an aperture with right-angled corners. Finally, removing and replacing glued-on but rotten headlining is a terrible job, and one I would not repeat. The glue + rotten foam mixture is almost impossible to remove!
For europe-based buyers looking for this type of boat, the Baltic is a good place to look. The majority of boats remain in the Baltic, have a short season, and are stored under cover during the winter. Owners often spend more time polishing and fettling than sailing. No criticism intended, I enjoy a bit of fettling myself.
Regards
Bill

John Harries

Hi Bill,

Just working on a budget post. To that end do you have a rough idea of what the new chain plates etc for your Rustler cost? Feel free to email me if you don’t want to make that public: https://www.morganscloud.com/members-priority-contact/

Bill Attwood

Hi John
I actually replaced my stainless with NiAl Bronze which worked out pretty expensive. I’ll look out the actual costs in my invoice file, but I doubt anyone else would be nuts enough to follow my example. Unfortunately I can’t give an exact figure for replacement stainless plates. I phoned Rustlers and asked what they would cost. From memory they were about £70 each for 6 chainplates. I would guess that they would have been supplied as blanks, so there would have been additional work or costs for drilling the boltholes. The Rustler 36 chainplates do have the great advantage that they are straightforward steel bars, and subject to a little carpentry, all the bulkheads are accessible. So, my experience is probably not very relevant. As Colin points out, some chainplate systems are much more complicated, and if the boats are no longer in production, the costs of fabrication might rule out replacement. I also wonder whether Colin’s point about the 3-in-1 type of chainplate shouldn’t rule out any boat which has them, unless replacements are economically available?
Yours aye,
Bill

John Harries

Hi Bill,

That’s very helpful, thanks.

Richard Elder

Hi Bill
Back in the day when I built my Cape George 36 I had Newfound Metals cast every bit of hardware from silicone bronze. All I needed to do was give them a wooden plug for the item I wanted. So there was no SS in the boat except for the rigging. Not only did I have forever hardware, but it was cheaper than Stainless Steel at the time. Now NM has their port lights and other items built in China, but there are still small bronze foundries around in the US if you look hard enough.

I believe there is a chainplate specialist on the East Coast that produces titanium chainplates to order. I think Andy from 59 North had some experience with them. Might be worth tracking down—.

Richard Elder

Hi Colin
Second only to teak decks on fiberglass or metal boats as Inventions Of The Devil is the fake dog hair production builders love to glue onto the insides of hulls and overheads.

Hi Dick
Your method of bedding and attaching chainplates (and every other item) to decks should be in the Bible that everyone who designs boats or works on them should be required to memorize word by word!

Richard Elder

Hi Colin
Since we are discussing all the ways that chainplates have been attached to fiberglass and composite hulls in the wrong way, it behooves us to mention the right way!
My friend Kurt Hughes has been designing them this way for 20 years.

“Composite Chainplates
December 17, 2019 Kurt
I recently had to review a chainplate on one of my COI cats and send a note to the USCG.
I see from the X-Ray report that the Aolani chainplates were not steel, but composite as I thought they were.
These composite plates are immune to corrosion, unlike metal ones.
I assume the builder used my layup schedule as I have sent earlier. I see no reason to doubt that.
They are easy for the builders to build in a huge safety factor.
Instead of being fastened onto a hull, these synergistically combine to both strengthen the hull and the chainplate.
Unlike the metal plates, these have some resiliency so make all the parts longer lived.
Any delta in the parts from the loads would show up immediately and early by cracks in the paint. Unlike metal plates which usually are not painted.
Attached find a picture of one of my other catamaran designs with composite chainplates. Note that he lifts his entire vessel with only the three chainplate locations.”

If readers want to see a photo of the 45′ x 228′ catamaran hanging from her chainplates go to” http://multihullblog.com/

ps” I assume these chainplates are fabricated from unidirectional glass, as there is no need to restrict the volume of material down to that for which carbons’ additional strength would be required. Therefore the materials cost of the chainplates is less than almost any metal design.

Richard Elder

Hi Colin:
One of my all time favorite designs is the Shuttleworth Tecktron 50 (Originally called Neptunes Car) from that era. Pure sex appeal. I saw her in Bequia when she was being operated by a French skipper as a transatlantic sail training vessel. I don’t think you could get non-French customers from the US to pay to cross the Atlantic on an open bridge deck catamaran though—-.

Richard Elder

If you really don’t like the idea of sailing with a big stick overhead that is fastened to the boat with a material like stainless steel with a proven failure mode, here is a source that will build almost any style of chainplate out of naval bronze. https://www.porttownsendfoundry.com/chainplates

Dick Stevenson

Hi all,
I have an article on replacing chainplates which has been on my back-burner for awhile. I consider this method to make leaks in this area far less likely and the re-bedding much farther spread out in time and (dare I say it) maybe not ever necessary again.
In short, it involves making a plinth of fiberglass that encircles the chainplate and gets epoxied to the deck (precluding standing water in the area of the chainplate). The other key component is butyl rubber making a very long-lasting (dare I say permanent) seal that withstands chainplate movement and stays pliable: never hardens.
Some of my chainplates bedded this way now have 6-7 years and many miles without a problem.
More details if there is interest.
My best, Dick Stevenson, s/v Alchemy

Philip Wilkie

On reading this article I kept thinking ‘metal boat, metal boat’. Then I went over to Colin’s excellent 2012 article “Thinking about a Steel Boat”. It’s stood the test of time and on re-reading it I’m finding valuable details immediately applicable to my own current refit. The great thing about steel, it has one failure mode, it’s pretty obvious and it can be fixed.

There are of course many, many superb GRP boats out there, it’s the dominant material for good reason … but crucially in the target budget range we’re talking about here … as this OP outlines, has many traps for the uninformed and unwary. For the relative novice, there is much too high a chance you’re going to finish up with a project boat, when you really weren’t expecting it.

Here’s what I’ve learned. The people who are most likely to be happy owners, and out there sailing as distinct from rebuilding, found their boat through a network of family, friends, crewing or club membership. In many cases they’ve found wonderful bargains that never got near the internet or a broker, because the previous owner was happy for their well cared for, beloved old friend was to go to a good home, with good people they liked.

John Harries

Hi Philip,

Yes, steel has it’s advantages, but on the other hand many of the horror-refits I have seen involved steel boats, probably a higher percentage that GRP, it’s far from a panacea. As a general rule, if you want metal I would look to aluminium, not steal. There are some Ovni’s around that are a great value and generaly owning aluminium will cost less and be less aggravation in the long run.

Not saying that a steel boat is never a good idea, but do be very careful if going that route.

More here: https://www.morganscloud.com/2019/05/30/hull-materials-which-is-best/

And we have an article coming from Colin on steel.

Philip Wilkie

I’d cheerfully commit a significant crime for a decent alloy boat … but here in Australia that immediately blows the U$100k budget (aprox A$150k) into the weeds. I’d need to start with a reasonable hull and rig for under A$70k and while nothing is impossible, it’s very unlikely. By way of a contrast, I’ve been on board a fantastic local OVNI 435 that was bought for around A$400k and then had a similar amount spent on it by one of our very best boatbuilding yards. Beautiful beyond words but totally outside the scope of this series of articles.

John Harries

Hi Philip,

Yes, I hear you on how much more expensive aluminium is. And a good steel boat can sometimes be less expensive. But what I need to point out is the danger of ending up with a really big steel boat problem and then going on to spend the same as would have been spent on an aluminium boat, plus years of work, trying to fix it. Or even more tragically, just giving up—look around most boat yards and somewhere there is a rusting relic that has gobbled some poor person’s dreams.

Philip Wilkie

John,

I hear you. There’s exactly one of those hopeless relics not 50m from where I am parked. Fortunately I think I got lucky with the hull I have, everyone who looks at it says it was well built and everything unbolts on the inside. It’s not perfect, but it’s better than 99.9% rust free. I bought it for around A$60k and the total budget will be a tad over $A150k.

The big change I am making is getting everything, and I mean everything, all the plumbing and wiring out of the bilge. White epoxy only. That way I can routinely degrease, desalt and hose it out with fresh water. I’m welding up virtually all the deck penetrations and the remaining few (for three winches and traveller) holes will be oversized, thru-painted and nylon shoulder washers with big backing washers.

The jib and staysail tracks are a big weakness because the usual row of holes drilled into the thin 3mm deck steel are high stress points and the paint breaks down underneath. I’ve devised a cool method of drilling and tapping a length of 20x20mm square steel section to match the existing track, then blind welding up the bottom of each hole. Then I just cut open a long thin 20mm section of deck where the old holes were and MIG in the new section half in and half protruding. No more holes to leak and the point stresses on the deck are far better distributed.

Everywhere else I’ve using another nice trick shown to me. For handrail stand off, for example, using a 50mm hole saw I just cut a hole in the 3mm steel. In the workshop I cut out another circle of 5mm steel using a 52mm OD hole saw that has a 50mm ID, then we weld the stainless component onto it directly, clean up and gritblast. Now it’s dead easy to just MIG the new part into the hole out on the boat in one simple clean operation.

The tradies I’m working with here tell me the secret to good steel repair is MIG or TIG onto clean steel with the right rod and heat, never overlap the joints, closely shield your argon to eliminate porosity, flapper off smooth immediately, a quick dab of phosphoric acid, degrease with an alkaline soap, and then lots of modern surface tolerant epoxy. And when in doubt cut a bigger hole than you think, steel plate is cheap. But as you say, if you can’t get to the inside, it’s all a waste of time.

Apologies Colin/John if this comment front runs another planned article. I’ll hit the pause button here.

John Harries

Hi Philip,

Wow, sounds to me like you have steel boats cracked! That said, it sounds like a lot of work, but then when were boats ever easy.

Richard Elder

Hi Philip
Steel boats may have only one failure mode but it’s a biggie! Rusting out from the inside.

I’m thinking of a Brewer Atlantic 45 I came across in Trinidad a few years ago. It had been sailed around the world by a guy with an onboard welder who had stopped at various locations along the way to weld patches over the rusty and leaking parts of the hull. When he arrived in Trinidad he paid to have it extensively re-plated, faired, and Awlgripped. As is standard practice in Trini the welding was done outside in the continual rain and humidity, then sandblasted before painting.

The beautiful paint job hadn’t begun to show its undergarments yet, and a young newby couple happily bought it. Five months later they offered it to me for $15,000.

My take away is that I only want two types of steel boat: 1: The rare one built like a Waterline or the one featured by Colin a couple of years ago. or 2: A steel boat with a simple interior bolted in place and easily removable for access to the hull interior.

Bill Attwood

Hi Dick
Chainplate plinths are an excellent idea. Mine are of teak, bedded as you suggest in butyl rubber.
Regards
Bill

Bill Attwood

Hi Richard
Unfortunately the boating world of the Pacific Northwest might as well be on another planet. It took me a long time to find the right supplier of NiAl bronze (how many tons would you like?) and as for titanium, forget it. ☹️ A visit to Port Washington is on my bucket list.?
Yours aye
Bill

Martin McOmber

For those looking for a better alternative to SS chainplates, there is a company in Washington State that specializes in affordable titanium chainplates and a host of other marine fittings. They do most of the work in house. Allied Titanium (http://www.alliedtitanium.com/). We used them to replace the chainplates on our Passport 40. Cost was about 20 percent more than stainless, but worth it to me. Might be more now, so please check. I shaved a few more pennies off by not having them polished. I like the gunmetal grey.

Alexander Hubner

Good evening,
To my opinion a good steel boat has much less maintenance than some people might think.
The key is find a boat with professional sprayed on foam isolation and later sandblast and epoxy any rust you might find. And buy a yard built boat in the Netherlands from a good designer like Koopmans, van de Stadt or Zaal for example. The Dutch know how to work metal.
Un saludo
Alex

John Harries

Hi Alexander,

Absolutely, those well built Dutch steel boats can be great, but, if still in good condition and well taken care of, they also tend to be expensive. Also, after a few years and paint jobs, they are often more expensive, as well as a heck of a lot more work, than an unpainted aluminium boat.

Ernest E Vogelsinger

Regarding steel boats: I just had found a YT channel of a young german couple (https://www.youtube.com/channel/UC28IeNb9dOlDCtn9FEpxrYA/videos). Unfortunately only in German so only for those who can understand this somehow eerie language 😉

Baseline: they bought a used Reinke Secura for 18k Euro (approx. 20k USD). They had much more work than anticipated as they even found rusty holes in the deck beneath the teak (they removed it completely), and refitted everything for around 40k Euro (approx. 44k in USD), mostly by themselves, using their weekends and vacation time. The outcome is quite astonishing, from a technical view as well as from accomodation. They also put in new equipment for approx. 20k Eur (22k USD), so the whole project sums up at around 88k USD. All the sandblasting, welding, and rigging has been done by professionals – so yes, the goal is achievable even with a rusty steel boat.

John Harries

Hi Colin,

I agree. Certainly beyond me, and I have taken on some intimidating projects in my day.

John Harries

Hi Ernest,

That sounds good, but what I’m learning as I work on the budget part of this project (lots of calls to experts so far) is one needs to be really careful about evaluating these kinds of final numbers. For example does that include all the stuff like rigging, sails, reliable engine, wiring, self steering, electronics, and on it goes? Maybe it does in this case, but if so I’m totally amazed.

Ernest E Vogelsinger

Colin, John, I absolutely agree that teak on steel is a straight way to desaster… and something I will avoid like hell when looking for my own boat. However, given the sheer possibility of age-induced issues/failures with GRP where one would possibly spend a couple of thousands just trying to spot the weak spots (pun intended) I believe going metal is still the better way, especially when looking for an aged boat having very limited budget. And there steel is still remarkably cheaper than aluminum. But I agree that one has to look very, very carefully around all corners when inspecting. And I wouldn’t bypass a suveyor who has a proven record of surveying steel boats of age.

BTW, they are very open with their budget in one of the later episodes after the primary refit had been finished, that’s where I took the numbers from. But the amount of work they put into that themselves is astonishing, for almost two years they drove every weekend from Munich to Italy to work on the boat, just to return on monday for their jobs. Neither their time, nor the travel costs (which must have been substantially) are included in that number.
They didn’t change the engine, but had a new Genoa (main was ok), replaced all wiring, new batteries and chargers, new autopilot plus Hydrovane. And lots of new electronics like new Radar, Plotter, AIS, VHF. They changed the shrouds and stays, had the mast dropped to replace all sheaves and in-mast wires, and pulled new halyards while at it.

John Harries

Hi Ernest,

I have to say that I find it really difficult believe that surveying a steel boat properly would cost any less than GRP. In fact I would guess the exact opposite would be true. Here’s a good piece on the required ultrasonic thickness gauging for steel yachts. And note that the surveyor recommends this process every few years. Also note that he says: “If the boat is 30-40 years old it is very likely there will be areas of unacceptable diminution or potential holes if steelwork renewals have not been kept up to date. I think it is guaranteed for steelworks to be required on that age of boat.” http://www.walshsurveyor.com/ultrasonic-thickness-gauging-of-steel-or-aluminium-yacht-hulls/

And that’s just the sonic survey, what about the disassembly required to get into ever corner where the boat may be rusting out?

No way on earth that I can see this costing less than a good survey of a GRP boat.

Colin has good contacts in steel boat surveying and will be sharing really good information in an upcoming article.

Scott Grometer

Alex,
I have desperately wanted an aluminum boat the likes of the Boreal 44/47 (even moreso since reading the recent articles here), but the dearth of any used examples for much less than new (and consequently way beyond my current budget) made me turn recently to again thinking of steel. I found one steel Koopmans here in the states that seemed–on the surface of things–to be interesting. I did considerable digging around on the internet and managed to find a twelve year old survey posted for the very boat in question (what are the odds?). The boat listing claimed a plate thickness of 1/8″ from the sheer to the keel. This already seemed lighter than I would have preferred for a boat with high-latitude aspirations. The survey that I (very thankfully) found revealed that this very boat with ostensible 1/8″ plate thickness actually measured out between .075″-.095,” with something like an average thickness of .090″ during ultrasonic sampling twelve years ago. The thing that I find remarkable about this is that the interior/bilges of this boat looked immaculate. This brings me to question the frequent assertion that steel boats ONLY rot from the inside out. Further reading of the posted survey suggests that the vessel had been thoroughly blasted prior to re-coating. Whatever the cause, this apparently well-built and very well cared-for steel boat had already lost considerable plate thickness–and that was twelve years ago. I like the idea of steel boats, and I have looked at many, but I also have to say that the potential hidden problems really scare me. Until someone can convince me otherwise, I am going back to looking at used Ovnis–at least until my financial situation will accommodate a Boreal.

John Harries

Hi Colin,

So true. A few years ago Steve Dashew was faced with selling his dad’s aluminium Deerfoot, one of the first built. The prospective buyer had the whole boat gauged and the finding were that there had essentially been zero plate wastage. If memory serves the boat was some 40 years old at the time.

Philip Wilkie

There are really only two reasons why steel plate gets thinner with time, rust or excessive sandblasting.

For outer surfaces under the waterline there is only one way to do it … carefully blast back to the required standard then at least five full spec coats of something like International’s Interprotect or Jotun’s Jotamastic 90. This should last at least 15-20 years if maintained reasonably well.

Incidentally the modern way to prepare the steel now is wet blasting, far less dusty and intrusive, and well within the reach of DIY. The key trick here is an additive to the water that inhibits flash rusting and eliminates any trapped chlorides. For example: https://blastx108.com.au/

Alexander Hubner

Hi John and Colin, I agree that an unpainted aluminum hull is the best maintenance wise.
I just meant that a good steel boat has no more maintenance than a grp boat. Especially in the light of all the possible problems that Colin described in the article. With the price you might be right as well, even though there are quiet a lot of boats on the market in the Netherlands. I guess you can get the boat for your target price and even make the necessary repairs but than there is the fitting out. So yes probably more . Do you have to pay a tax if you bring a european boat to the states?
I don’t want to get into this old discussion aluminium against steel. I like both materials, but I have far more experience with steel. I think that a problem for the reputation of steel boats are the huge differences in built quality. Due to a lot of do it your self projects and even so called professionals that don t understand the material. Here in Spain for example nearly all the leisure boats are GRP so it s not so easy to find skilled worker for a steel repair in the typical marina. But I stand firm to my point that a boat from a good designer, built from a good yard, in the hands of a skilled owner can last nearly forever. But the 3 points are important. For example the Koopmans mentioned above. I am sure that the design is fine, but all the rest is not in the hand of the designer. I have a van de Stadt from 95 and I had to put some work in her but now she is as good as new.

Regards from Bilbao
Alex

Denis Foster

Hello Colin and John,

Thank s for this very informative chapter.

Can you give more precision on two topics :

1) Teak decks on GRP decks.
I understood that until recently around 2005 the teak was glued to the deck and the SS screws that go in only the solid laminate upper surface are there to hold the planks while the mastic used cures. Once that it completely cured the screws are not really necessary and the hole can be filled with PU and a tight bung will keep that dry ?

2) That Butyl correctly used is one of the best ways to seal durably a fixation of SS deck ware since it allows some elasticity.

Best regards.

Denis

Dick Stevenson

Hi Denis,
With regards to the butyl rubber part of your question, the best writing “how-to” on the subject is one of RC Collins superb picture essays (https://www.pbase.com/mainecruising/boat_projects) on using butyl rubber in just the way you ask about.
If you find this article, and the many others, as useful as I do, please consider donating to his free site.
I have been using BR for all/most deck bedding for more than a decade without a problem: in fact, I consider BR far superior.
My best, Dick Stevenson, s/v Alchemy

John Harries

Hi Denis,

As far as I know, most teak decks before around 2000 were put down with polysulphide based compounds. (Boatlife being a common brand.) This was the case with my boat.

Polysulphide is great stuff, and I’m a huge fan, but it’s not a great adhesive, so the screws do have a function. Also, the upper laminate on a typical cored deck is quite thin, so in most (probably all) cases the screws would have penetrated the core. Or to put it another way, no way the average boat builder is going to drill a hole no more than 1/4 deep without going through to the core. And if they tried, the screws would tend to pull out when the the worker screwed them down hard enough to properly compress the bedding compound.

Around the mid 2000s (guess on date) some builders started glueing the decks down with no screws at all using vacuum bags to apply the pressure. I looked at a Halberg Rassy at the boat show done this way, and have seen others, and this looks like a very good way to go, at least if one must have teak decks, but as far as I know it’s only been happening for the last 10-15 years.

Summary, for boats of the age we are talking here, the screws are required and almost certainly penetrating the core.

Bill Attwood

Hi Denis
Not sure if clean-up of butyl rubber will be found in your research. Terpentine is an excellent way to do it. Clean squeeze out mechanically as much as possible, then use a rag soaked in terps substitute. The normal stuff available in every diy store. You need plenty of paper towels!
Regards
Bill

Denis Foster

Thank’s to all for your replies and sharing your knowledge. I always take good notes of topics on aging boats since as time passes our boats (and ourselves) approach refit time.

May I ask you what sealant should be used for the diesel filler ?

We are the happy owners of a Hallberg Rassy 46 built in 2003, so we have the teak deck with Torx flathead screws. We take meticulous care (John would describe this as anal obsessive behaiviour) of the teak deck in the hope it will last another ten years if possible.

Best regards.

Denis

John Harries

Hi Denis,

I like Boatlife for most things: https://www.morganscloud.com/2016/08/08/goop-and-goo-and-why-i-hate-5200/

That said, although I have not used it much, butyl rubber has a great track record with people I trust, particularly in areas where there is some flexing, not generally a problem for me as my aluminium boat is very stiff.

I’m pretty sure either would do fine

Terence Thatcher

Regarding stainless: Each of my shroud chainplates at deck level rely on 4 3/8″ or 1/2″ stainless bolts. (Can’t remember which right now.) In all cases, I can easily, and do, regularly inspect for leaks. Well bedded, only one has leaked. Here is my question: should I replace the stainless bolts on the non-leaking chainplates? They may be 40 years old and pass through the solid GRP deck (core exists elsewhere in the deck but is absent at the chains). Does dry stainless simply wear out in time? Thanks.

Eric Klem

Hi Terence,

To answer your question, it is important to think about the failure modes.  In general, stainless is a pretty stable material which doesn’t degrade just with the passage of time but there are a few key issues that can arise.

If anything has visibly yielded or if a new nut will not go end to end on the threads easily, the bolts are definitely bad.

Crevice corrosion is a nasty failure mode that you have to watch out for and you have to be really confident that the bolts really stay dry to rule it out.  If there is any rust staining coming from an enclosed area, that is definitely something to be wary of.  If after taking the bolts out you can see any actual degradation, that is a definite reason to condemn them.  The trouble is that you may not actually see this.  Dye testing is another useful tool and in certain geometries, magnafluxing is even better.  But by the time you are talking about these sorts of techniques, you should usually just replace the bolts.  On the boat we own, the chainplates are 316 held in by 304 bolts to knees below decks and everything was bedded in butyl.  Now that the boats are 30-40 years old, many owners are starting to notice some leaks at their chainplates and many have reported being alarmed that a few of the bolt heads snap off at very low torque and pictures show that this is due to crevice corrosion from very small leaks.  On our boat, we had 1 leaking plate that we caught pretty quickly and had 1 compromised bolt which was just starting to show rust staining.  In our case, we replaced all bolts with 316.

 When dealing with fatigue, if it is properly designed in the first place, this should not be a major concern provided that the joint is not moving.  Steels have what is known as a fatigue limit where as long as the stress is below a certain level, you can cycle it for as long as you want and it will never fatigue.  This value is usually around 50% of the yield strength but does depend on the alloy.  In something like a chainplate, it would be pretty bad practice to design it so that the stress went over this value, it could certainly happen but it shouldn’t.  Where you may get in trouble is if the loading is uneven such as prying up 1 side of the bolt head which could locally go over this fatigue limit and start a crack that then propagates but again, this would be poor design but it does happen.  Fatigue in bolts is actually much more complicated than this and generally in a good way.  Fatigue relies on cycling, if something is held at very high stress but the stress is not changing, there is no fatigue.  So in a joint where a preload can be created and held, if the preload in the bolts is higher than the load that will be placed on them if there were no preload, the bolt actually experiences constant tension/stress and therefore will not fatigue.  This is part of the reason why we try to torque bolts to something like 75% of yield strength, it actually improves fatigue performance rather than hurts it.

Eric

John Harries

Hi Eric,

I’m working on a pro-forma budget and that’s really useful information, thank you.