Cole 43 Yachts

[sildene]

I have taken the liberty to start this new thread dedicated to Cole 43 yachts to resume a discussion that was progressing under the Meets & Greets heading. The discussion seems generic enough to warrant this distinct thread.

Martin

[sildene]

Originally Posted by captncruise

Hi all you fellow Cole 43 owners. My wife and I have owned and sailed Bacardi for the last 15 years. Bacardi was the first Cole 43 out of the mould in 1970. She was Peter Cole's own boat.

We haven't examined the keel bolts but earlier this year I noticed the strop that comes down from under the deck to the keel/mast step was loose. Closer inspection revealed the mast step had almost rusted away. After 3 days of drilling, griding and cutting we managed to get the old step out. Andrew Raoke, shipwight at Yamba Marina, was a great help and fabrictaed new S/S maststep for us. While we were at is we decided to remove the chain plates and found they both had hairline cracks about 3/4 of the way across. Andrew made up new chain plates and we were able to get back to Broken bay without losing the mast.

We plan to sail back up to yamba next April and haul out to re paint the hull and will probably drop keel as weell to check keel bolts.

Keep your eyes on your tell tales

Graham

Welcome Graham, and thanks for sharing your experience with the mast step and chainplate hairline cracks.

I hope to pull my mast before the end of this year, and have been wondering whether its worth removing the chainplates. With the fore and aft lower stays, there are six chainplates plus backstay plate and bow stem fitting. Not a trivial undertaking - did you remove all of them? If you did, how many showed signs of defect?

When talking about Cole 43 chainplates, you have to mention the seamanship of Tony Mowbray aboard his Cole 43 "Sal". Circa year 2000 he circumnavigated solo via Cape Horn and Cape of Good Hope (... routine looking sentence ... ). Before reaching the Horn, the Cole's port shroud chainplate broke in two, but the sea state allowed the mast to stand. So he spent three days drilling holes in the port side hull; fitted a backing plate inside the hull and set up a multi-line spectra replacement for the port shroud, using pulley blocks to gain advantage to tighten the lot. And sailed on. Past the Horn and Good Hope. Good sailor.

The chainplate on his Cole actually has a bend a few inches under the deck. Because the main bulkhead is one or two inches ahead of the spreader tip line, this 'kink' bridges this bulkhead offset to align the chainplate directly below the spreaders. To avoid metal fatigue at the kink, a thick SS knee was welded in, but somehow (not sure how) the port side knee on Tony's boat was defective, and thus gave way.

However, it must have been a small defect since the plate held up for a long time, including the 1998 Sydney-to-Hobart, in which Sal was dismasted.


My Cole's chainplates are straight, and in good condition everywhere they are visible. I assume your hairline cracks appeared in the invisible part - where the plate passes through the deck?

Do you mind indicating your rigging wire diameters - I have 3/8" wire for shrouds, headstay and backstay, and 5/16" for lowers. I am currently planning to replace the rigging and hope to cross the Tasman some time next year. Some have suggested that I need to increase wire size if I go for 316 stainless as opposed to 304. On the other hand, a local rigger has told me to stick with what the builder put in. Any experiences or suggestions re. rigging size on Cole 43's appreciated.

Martin

[GordMay]

Polaris of Belmont: Polaris of Belmont - Official Website
And: History

[captncruise]

Thanks for the reply. I know Tony Mowbray quite well having sailed in a Cabbage Tree island race on Polaris with him and helped raise money for the Kids Hospital.

I have a copy of his original Log Book of the circumnavigation.

All our rigging is 3/8 stainless.

The cracks in my chain plates were in the Main shroud chain plates. They were at deck level and would not be visible on inspection. Both cap shrouds and lowers attach to the one chainplate. The forestay and back stay chainplates were OK but I would probably replace if doing a complete re rig.
I am told that stainless has a half life of 7 years so after 37 years they arpast their use by date.

I have replaced the original baby stay on the front of the mast with a substantial forestay with Hifield lever. Also have added spectre running backstays.

The original engine was a Perkins 4107 which had 1:1 gear box driving thrugh a V Drive and the 2 blade prop was just behind the keel. The stern galnd was located in the deepest part of the bilge. The engine always leaked oil and one day the stern gland rubber came off having been softened by the oil in the bilge. We could have lost the boat. I managed to get the rubber back on but it came off again once we ran the engine in gear.

Since the original stern tube was in place I decided to turn the engine back around and open up the aperture in the skeg for the prop. Also replaced prop with 3 blade fixed prop. This improved handling under motor but did lose about 1 knot sailing!!!

In 2001 the gear box seized and we replaced the old Perkins with a new Nanni 43Hp, new shaft, dripless stern gland and Hydralign Feathering prop. What a differance, not cheap but no oil leaks or water from stern gland.. Can turn boat in her own length.

Please feel free to ask any other questions you may have.
Regards
Graham

[Ex-Calif]

Originally Posted by captncruise

I am told that stainless has a half life of 7 years so after 37 years they arpast their use by date.

Pardon me for butting in. Be careful agreeing to statements like the above. Obviously a 7 years half life is not accurate if yours lasted 37 years!

More accurately is that all metals used in basic construction will start to corrode once in service. The corrosion leads to local weakening and/or stress risers. Cracks under load will show up in the stress risers.

A couple of things that help accelerate are bends and bends "at the deck" or anywhere water can accumulate. Bends are a natural stress riser and coupled with pooling water at a bend allows corrosion to set in at teh bend. The worst of both worlds.

So how does a rig last 37 years? Predominantly if the rigging system is massively overbuilt it can sustain the stresses even with corrosion and stresses in the bends.

Overbuilding the rig makes for a long lasting boat but adds weight and windage. However it does add significant peace of mind when you are in heavy weather.

It's hard to judge when to replace the rig but eventually time takes its toll. Again generalizing but on "production" boats I believe the rigs are engineered "just right" and with the standard safety factors built in these rigs 7 years +- is the right time to get serious about maintenance. On hand built boats and "blue water" boats the rigs tend to be more overbuilt and likely can go longer. Sometimes much longer.

[GordMay]

captncruise & Ex-Calif:
Your use of a 7-year “half-life” analogy* needs a little clarification.
By half-life, do you mean, at 7 years:
- half the stainless parts have failed? (at 35 years, 3.125% of parts remain in service)
- half the stainless steel (mass) has eroded? (at 35 years, 3.125% of the S/S remains)

* Half-Life usually refers to radioactive decay, where half-life (for a given radioisotope) is the time for half the radioactive nuclei to undergo radioactive decay. After two half-lives, there will be1/4 the original sample, after three half-lives 1/8 the original sample, and so forth...

[sildene]

Originally Posted by Ex-Calif

More accurately is that all metals used in basic construction will start to corrode once in service. The corrosion leads to local weakening and/or stress risers. Cracks under load will show up in the stress risers.

Very welcome input, Dan. What are "stress risers", and can you detect them with dyes or 20x optical magnifiers?

From what you say, can one infer that, if a chainplate is a simple, straight, overbuilt piece of 316 SS exhibiting no corrosion, the metal must be good; or can metal fatigue be present although invisible? If the latter, can it readily be tested for strength?

If fully toggled turnbuckles were used on the straight chainplate (and no corrosion is present), where would the fatigue be concentrated?

Apology for all the questions, but you clearly know more than me about this topic, and it is a pressing one for me right now.

Martin

[GordMay]

Stress Risers are places where stress lines, from applied forces, concentrate within a part, amplifying the applied stress at that position.
A stress riser provides a starting point for subsequent a crack or tear (fatigue).
Stress concentrations (amplifications) generally occur at small flaws or cracks (which can be detected visually & with dye), and can also occur at sharp corners, holes, fillets, notches, changes in the cross-sectional area of the part.

[Ex-Calif]

Originally Posted by sildene

If fully toggled turnbuckles were used on the straight chainplate (and no corrosion is present), where would the fatigue be concentrated?

Martin

Gord posted an excellent description of stress risers.

Let's assume a flat chain plate with 6 mounting holes that strap on the outside of the hull and two drilled eyes where the turnbuckles attach.

The stress comes from the two turnbuckles and is transmitted around the two turnbuckle holes where the turnbuckle pins contact the chain plate.

Note the contact area is very small so the stress concentrations are very high - this could be considered a stress riser. The load would be highest against the vertical pull of the turnbuckle at the contact point and distribute around the upper 180 degree area of the drilled holes. If it failed here it would likely be tensile overload followed by tearing anywhere in the upper 180 degrees but most likely at 90 degrees to the load.

The lower 180 degrees is less stressed and transmits the load vertically through the chain plate to the 6 bolt holes. The loads here are similar to the loads on the tunrbuckle eyes but reversed. Any of these holes that failed would likely show up as cracks at 90 degrees to the load or small stress cracks at the bolt contact area.

In addition to the bolts and turnbuckle pins there is probably bedding of some kind. This contributes very little to the structural strength.

Things to be conscious of.

1/ Dings, nicks and corrosion pits in the bolt holes, especially the upper turnbuckle eyes. Any of these conditions creates a stress riser at a very critically stressed area.

2/ Dings, nicks and corrosion pits on the edges of the plates. The edges are also pretty highly stressed.

3/ In general load bearing plates in tensile load should have smoothly radiused ends. This distributes the load even around the end of the plate. Plates with sharp corners will tend to focus the stresses in those corners.

4/ The other place (as noted in previous posts) is anywhere they pass through structure such that water pools and inspection is difficult. It is very difficult to see the corrosion happening here and even if there is no actual bend in the plate there are lateral bending (flexure) loads imparted in the plates where they pass through decks.


Just a note on half life - that term is bandied about a lot. It's meaning is rather complex depending on the elements involved. A better description of what is happening is that a part designed with X amount of stress margins has it's load bearing capability reduced depending on its in service condition - i.e. corroded, nicked, dented, etc. When the margin is gone the part fails.

There must also be a flexure failure mode ongoing as well. The chain plates will flex along with the rest of the rigging. At some point the work hardening will reduce its load bearing capability.

If you have an opportunity to replace failed chain plates and they lasted 37 years, I would go with original design. If they lasted 7 years (like mine) you can upgrade (I did) and see how the life works out.

If they have never failed, you'd like to find out about failures on similar types, consider if the operating regime is the same as yours and then change them before failure.

[captncruise]

Thnks dan,

The chain plates actualy pass through the deck and are bolted to the main bulkhead. I had seen boats with similar design where water had weakened the bulkhead around the bolts causing the plates to be pulled up and loosen the rig. I always kept a good eye on this possibility. There was never any sign of this on my boat.

Another boat the same design as mine but with differant rig set up, had a major rig failure during a solo circumnavigation. I only pulled my chain plates because they were 37 years old. The cracks were very faint but ran across the plates approximately where they passed through the deck. The holes where the rigging screws went were also slightly mishapen.

New plates have been fabricated by Andrew Roake shipwright at Yamba Marina NSW Aus.

Keeping an old boat going takes a lot more that a bottom scrape and varnish.

[sildene]

Originally Posted by captncruise

I have replaced the original baby stay on the front of the mast with a substantial forestay with Hifield lever. Also have added spectre running backstays.

Graham

Thank you for good information, Graham. I'll remain with the 3/8" rigging wire. Also useful to know the 3-bladed prop noticeably slowed you down. I'm still using a stuffing box as seal, but am fitting a Vetus Bullflex shaft coupling advertised to reduce vibration and accommodate a minor amount of shaft misalignment (which I understand is always difficult to eliminate altogether). Once I re-install the Bukh engine (rebuilt), I'll know whether it makes a difference.

Very keen on setting up a forestay myself. When installing yours, I assume it was in a different deck location to the original baby stay. Why did you choose not to leave the baby stay in place to provide additional support?

Below deck, did you anchor the forestay via cable and chainplate to a bulkhead in the forepeak, or did you find a better way?

And, when anchoring the running backstays, was it sufficient to use large horisontal backing plates under the deck, or did you opt for something more elaborate?

Regards
Martin

[sildene]

Dan, there's a lot to learn from your post; certainly know your stuff (engineering graduate?) Much appreciated.

Martin

[captncruise]

We carry the dinghy between the mast and inner forestay, so the baby stay was in the way. Also it was adjustable by a line that ran back to the cockpit and was one more line to trip over. Would probably be usefull for tuning while racing but we don't race.

The new inner forestay is attached to a stainless fitting custom made to fit around mast section. The back stays attach to lugs welded to this fitting.
At deck level there are turning blocks attached to the Jib turning blocks. These are mounted on big blocks of teak through bolted through the deck. There is a Barber hauler that pulls them forward when not in use.

The lower end of the forestay has a Hyfiled lever that attaches to a chain plate. This chain plate goes through the deck and is bolted through the bulkhead between the anchor locker and the forward cabin. There is also provision for a strop to the bottom of the bulkhead which is removable to give access to the chain locker.

I find it difficult to describe this in text. Maybe if you send me your email address I could send some sketches if the above iss not clear.

Do you have any history of your boat? Was it originally a differant name?

Regards

Graham

[Ex-Calif]

Originally Posted by sildene

Dan, there's a lot to learn from your post; certainly know your stuff (engineering graduate?) Much appreciated.

Martin

Thanks. In the interest of full disclosure I am an engineer but prefer to refer to myself as a generalist rather than a specialist. My main talent is being able to work with the specialists and translate their output into information that mortal people can use.

We have wickedly smart mathematicians, structures, materials and every kind of specialist you can imagine. I know enough to be dangerous and enough to know when to call the specialists and enough to know when to put two specialists together and get the heck out of the room.

[plane sailing]

last november i bought a cole 43, named Cadence she was previously called chikadee and fowl play. i would like to find more of her history, particularily her circumnavigation in 2006-2007. if any body knows ANYTHING please let me know. shes a beautiful boat and sails with a great motion we love her and are preparing her to take off again.
Paul.