CARIAD REPORT #8
PLANKING – AN INCONVENIENT TRUTH
(4th April 2022.)
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Cariad was hauled out at PSS on 22nd March 2022 whereupon it immediately became clear that 12 years in the water at Raffles Marina without haul-out had taken its toll. Notwithstanding the three lower planks on both sides (expected) at first glance the hull condition appeared to be in reasonable condition but when we started to sand off the antifouling the true condition surfaced.
There is much talk of copper sheathing and types of antifouling on how planking can be protected from worm and rot in the future.
The answer is simple….. Timely drydocking and adequate ventilation.
** Difficult pending decision:
Do we replace the old iron behind the uncovered Garboard Planks or repair the existing iron and paint it before re-planking?
Option #1. Do not renew existing ironwork.
Pros.
The iron is 126 years old and rivetted to the floors. Clearly degraded, but is observed to still be in serviceable condition.
The marriage between the iron (believed to be Swedish Loma Iron) and the timber keelson is still OK.
Cons.
If we don’t renew that steel work, criticism could be levelled at us as to why we didn’t change it when we had the opportunity to do so. All the ironwork is exposed where planking has been removed. (See photos included in this report)
Option #2. Replace the existing ironwork with high-grade steel.
Pros
Might add strength to the original construction.
Original construction was very good but has been somewhat degraded over time.
Cons.
Welded, not rivetted, as before.
Difficulty welding where steel meets the timber keelson.
We would be grateful if you would advise your choice whether to renew steelwork or not.
Planking findings are in three categories.
Toredo worm,
Planks damaged by Toredo worm whereby the worm exhibits a small entry hole then begins to chew away at the interior of the plank. Internal damage does not become apparent until digging reveals all.
Rotten timber.
Vessel lay immobile for 13 years sitting in humid equatorial heat. Perhaps insufficient ventilation. Sweating occurred where timber sat hard up against steel (cheek plates in particular) which, in certain cases, created a water trap leading to rot. In these cases, the interior surface of the plank was found rotten but the exterior, which was in direct contact with seawater, was fine.
Besides planking, we have found severe rot in the stem and stern post areas.
Good planking.
Due to seawater sitting in bilges for prolonged periods some internal frames have corroded badly – mostly in the stern section. Amidships appears to be unaffected. To repair/replace this steel work the planking in way must be removed. Care is being taken to remove these planks without damage so they can be reused.
Summary.
30% of planking has been removed.
10% is in perfect condition and will be fitted back
20% needs replacing.
Stem and stern knee are worst damaged areas.
HULL AND KEEL SUPPORT SYSTEMS.
Hull side supports – 8 each side.
Exposed 126-year old iron work.
Worst area of the exposed ironwork.
Original steelwork is quite OK.
Extensive rot on planking located outside the steel longitudinal cheek plates. Steel found in good condition in way.
File photo 2007 shows massively strong inner steel work.
Rotten stem. Whole stem will have to be dropped and rebuilt.
REMOVING GOOD PLANKS TO ACCESS INTERNAL CORRODED STEELWORK.
Removing good planking to access internal corroded steel.
Good planking removed in order to access internal corroded steel.
Mike Howett inspecting overall condition.
Stern area is clear and ready for steel refurbishment.
Steel exposed and ready for refurbishment.
Stem section is worst hit.
** Rot from inside caused by condensation and lack of ventilation.
Paintwork under stem steelwork found in relatively good condition.
Rot in the rudder stock tube.
After stern tube removed steel appears in much better condition than we first thought.
Des Kearns
Cariad Project Manager
4th April 2022.
