Lift wire maintenance

During the last sail the swing centerplates lift wire got jammed into the case somehow, so the plate couldn't be raised via the control line in the cockpit. A small thing causing a major problem.

So it was back to the wylo yard to see what was causing this. 

Teria with big cousin a wylo2

Teria was set up on the keel stands so the centerplate could swing freely.

Inside the upper stainless lift pipe was removed. A storage locker was built around it so some gentle persuasion with a chizel and hammer here and there gained enough space to remove the pipe.

I used a lever handle with the lift rope wrapped around to free the stuck rope/wire join. Luckily the join didn't break in the process. It's a very small space in there. I often wondered what went on inside the lift mechanism, the rope to wire join was revealed for the first time.

Lift wire to lift rope join revealed.

Lower lift pipe and lift wire

The wire has a soft eye and swage, the rope has a soft eye and whipping.

The problem was the swage had got jammed into a slightly smaller hole (<5mm diameter) in the top of the case at the base of the lower lift pipe. The hole may be lined with a metal bushing glassed in to take the wear of the lift wire angling across it, but its really too inaccessible and small to see exactly how its made in there. The jam problem may have been caused by shortening the lift wire an inch or so during the centerplate restoration last year.

The rope-wire join looked good enough for reuse. But to avoid a re-run of the jamming i filed the rough bumpy bits off the swage, reducing its diameter a mm or so. After reassembling the upper stainless lift pipe , the tail end stopper knot was retied 6" shorter. This should prevent the swage from reaching the small centercase hole (which caused the jamming) when lowering the centerplate next time. 

Centerboard restoration and refit

The restoration began with knocking out the old plastic pivot bushing at the workbench, keeping it and other pivot bolt parts together so measurements could be taken to replace the entire pivot unit assembly.

The rust was removed, mostly with a power wire brush on a 5" grinder and 9" angle grinder with cutting wheel.

One thing that surprised me was the completely square edges on the 12mm thick centerplate. These looked very un-hydrodynamic so i set to it with the 9" grinder to reshape the forward and trailing edges into semblances of a parabolic foil shape to improve sailing performance.

There, that's starting to look better! A final bit of rust converter acid  to neutralise the deeper pits. The hot dip galvanising plant recommended some paint stripper to make sure no remnant paint remained anywhere as cold gal won't stick to paint etc.

A pic of what the center-case slot looks like without the plate, its a hardly-ever seen (let alone maintained) part of a trailer yacht, its either under water or on the trailer near the ground with rollers and steel beams all around it which prevent easy access to it.

The center plate of the 18 foot Teria is a similar size to the daggerboard of the 8 foot long Fatty knees dinghy. The Teria has a shoal draft fixed keel that makes up about 75% of the yachts lateral resistance, the center-plate is about 25% of the lateral resistance. The Fatty knees has only a 1" deep rub-keel and small skeg so it's dagger board does most of the work.

The pivot assembly was re-built from scratch. A stainless 10mm diameter bolt and the remains of the 3 bushes were taken around town to see what could be done. I started at the marine chanders, went to a power boat chandlers and they knew of an engineering firm just down the street - Arndt Engineering.. In luck, they had refitted yacht rudder shaft assemblies. The callipers were taken out, centerplate and pivot bolt bits were left with them, they made the bushes on a lathe with white polyacetate? a tough hard wearing plastic suitable for marine immersion for a very reasonable fee. They drilled out the pivot hole a bit and allowed for some clearance after the cold gal was on. The center bush was slightly larger than the original which made it thicker walled and stronger.

The center plate went to the galvanizing plant, it weighed around 20 kg which was just under the 25 kg minimum lot weight. So paid $55 for the plate's acid bath and hot dip in the molten zinc vat. The going rate for hot dip galvanizing at the Bohle plant is $2 / kg. Due to a long work Que it took a week to get done but it was worth the wait, it sure did look like new.

Back at the boat yard cheek pads were fabricated and fitted. I bought 2 mm black polyethylene? plastic sheet (aka chopping board plastic - is a bit slippery) at Northern Plastics. Cut round circles 270 mm in diameter with a 20mm hole in the middle.

The plate was refitted with the help of a friend. Mike got the pivot bolt in while i lifted the plate up. Some pencil marking and a strong torch helped align it. Afterwards it was apparent that the 4 mm packing was not enough the plate was too loose in the case and wobbled about. So i dropped it out and added a third 2 mm spacer.

This time i got it in solo and allot easier. The plates 20 kg weight was held up by the trolley jack below, when up in the case there's almost no fore and aft play so the pin aligned with the hole far more easily. This time, with  6 mm of plastic packing, the board fit snugly with no sideways movement.

The benefits of a "deco" floor, dug a small trench for centerplate to lower into.

Note: Decomposed granite "Deco" is an economical material often used for car driveways up here. It can be spread out like soil, but after being compacted (by cars wheels) sets hard. However it still remains workable, it can be added to or even dug through (eg to lay a pipe). It's great on the expanding clay soils we have, as it never cracks up like concrete. In the open, grass will grow over it. Under a roof it's resistant to grass and weeds, i just spray the few that do sprout.

The pivot bolt assembly got bedded down with liberal amounts of silicone sealant to prevent leaking.

Pivot bolt nut and washers inside the bilge area. The high compression plastic washers spreads load out while having a little "give" 

To refit the lift wire i bought a 3.2 mm swaging tool. It looks like a pair of bolt cutters but with a different business end that crimps the swage tight around the wire.
This time the eye was not integral with the plates lug, it was attached with a screw pin shackle instead, so future maintenance (possibly by some new owner?) will hopefully not require the purchase of an expensive swaging tool!

Lift wire now shackled to center-plate for easy plate removal.

Everything together - the plate worked well. Rising up into it's case with a haul on the lift rope in the cockpit. Lowering down by letting it out. I marked the lift rope with 2 positions, 1/2 raised and 3/4 raised. The system is simple, no purchase block and tackles required, just a pipe for the lift rope-wire, exit sheave and horn cleat.

Trailer removal and Blocking-up the hull

Some maintenance to center-board and trailer needed to be done - The centerboard was rusted into it's case and the trailer rollers and side pads were not letting the boat slide off as they should.

So the Teria had to be blocked up and have the trailer removed to work on these issues.

The Investigator forum had some good posts - It can be done at home in the driveway and another boat was done in a fully kitted out automotive shed with lifting slings - Gantries etc. Some owners enlisted a bunch of mates to hold the hull up to get it off the trailer. My method leaned more towards the at home method with modifications and the added benefit of a shed structure around it.

Teria was towed to my boat building shed out in the country. It houses my home-built Wylo 2 yacht hull , for full story see wyloyard. Over the last few years i extended the shed roof area, the west extension was originally  intended as the yachts' woodworking-spar workshop but now it was just right for use as a trailer boat repair shed.

In the wylo yard shed extension

The trailer removal began by lowering the front of the trailer to the ground.

This raises the stern up high and a 44 gallon drum with old car tyre and tarp padding was pushed under the transom.

Next i secured the hull  with strong ropes. This was to prevent Teria's  hull toppling over sideways. The ropes went through the u-bolt chainplates on deck. Two ropes went horizontally to shed posts to prevent side tipping. Two very strong ropes went up subvertically to the shed roof and could, in theory, hold the entire hull up in the unlikely scenario of the support stands failing or tipping out while i was under the hull.

More secure ropes were setup down aft to prevent the hull moving foward as the trailer was extracted..

Then the front of the trailer was jacked up again. This made the transom press down on the drum aft and the boat started to lift off the trailer. I did the lift-off because because need as much height under the keel as possible in order to remove the centerboard later, also the trailer was badly fitted and the hull was resting too heavily on the side pads, almost stuck there. 

Keel lifts off aft rollers

Hull lifts off aft side pads

The safety ropes were re-tightened to remove slack caused by the lift. 

To pull the trailer out, a come along winch was setup between the Ute towbar and trailer ball. 

As the trailer moved foward a car stand and car jack went under the aft keel. Hardwood blocks are used to protect the fibre-glass keel and to support or raise jacks and stands.

Hardwood side legs could now be fitted under the gunwales to further prevent the hull falling over.  (Allot of secondhand hardwoods from old wrecked houses up here. Bought my railway sleepers a long time ago from Queensland railways yards)

As the front of the keel emerged, the car jack was moved forward and a second car stand went under the front end of the keel. The two cars stands are placed so the centerboard case slot is exposed between them. The boat was jacked up level, stands adjusted to height and trailer pulled out for maintenance in my case.

NB. In boats with good trailers, a safer way to go is to leave the trailer in place to help hold up the fore-keel and stabilize the boat. Blocks should go under the back end of trailer, its brakes on and wheels chocked.

Rex inspects the job

I put a steel workhorse under the fore keel to further support the boat.With side legs and support ropes adjusted i was confident to go under the 900 kg hull without worry.