Calstar: transduced, not

Last Friday was supposed to be the big day. Rudder bearings replaced, anodes renewed, her bottom painted with a fresh coat of antifoul and her sides lovingly polished by Dad, the lift was booked for 1500 on Friday 28th Jan, and Calstar was to re-float.

The trip down to Portishead was uneventful, we arrived in good time to find the lift crew were running late, so Dad and I retired to a local coffee shop for a brew and a very sticky, very sweet almond croissant each that had proven irresistible, taunting us as it did from behind the coffee shop counter.

The day was calm and warm in the broken January sun. A pleasant day to spend on the dockside.

The lift finally turned up, it's crew strapped Calstar in with professional efficiency, lifted her off her blocks and walked her out of the yard, across the road and onto the slip.

The last thing I'd done before we lifted her was refit the speed transducer for the log. It had been previously taken out, the crusted up paddle wheel cleaned and replaced with a temporary plug when we'd last had her out for her annual tlc, a couple of years ago, pre-pandemic, in Plymouth. And then we'd forgotten to put it back.

The log, of course, gives us our speed through the water. It's hardly critical information, as the speed over ground that we read directly from the GPS via the chart plotter is a much more useful number. But I like measures and numbers, and it's a useful metric to have as it gives you an immediate clue as to how well the boat is sailing and, when compared to the speed over ground, what the tide is doing.

Plugging it back in seemed a simple, obvious thing to do. You can, in theory, do it whilst the boat is afloat, but I've never had the nerve for that.

The lads manning the lift paused as they lowered Calstar towards the water to let me climb aboard over the bow. I didn't anticipate any problems, but conscious that the transducer is fitted through the hull, I wanted to assure myself the fitting was watertight before we moved away from the lift.

It wasn't. It was hardly a flood, but a steady, incessant weep. I asked the crew to lift her back out, unscrewed, re-seated the transducer and screwed the cap down tight again. We re-floated. And still it came in, if anything, quicker and more incessant than before.

We lifted her back up, and I removed the transducer and replaced the plug that was in there previously, screwing it down tight. 

Back in, and this time there was a definite leak coming in through the top where the cap was screwed down. Conscious we were using up the lift crews' time and holding them back late on a Friday afternoon we had a hurried consultation and they offered to leave her in the slings over the weekend for us to work on the problem, then relaunch first thing Monday.

About an hour later, browsing the shelves of the local chandlery for some waterproof grease, Dad noticed a notch in the top of the plug, clearly intended to mate with an indent on the hull fitting, to ensure it could only be fitted one way.

It seemed obvious, in retrospect, in the dim light of the cabin, working in the bilge, I'd overlooked this and so mis-fitted the plug, and, presumably, the transducer before it. We returned to the boat, and Dad and I head down in the bilge with a bright torch greased up the transducer, located the notch and secured it into the housing. Confidence we'd identified the problem we went home for the weekend.

So Monday came around and, dead on 0900, we lifted her back up and re-floated.

Dad and I climbed aboard over the bow, and heads down again in the bilge with a bright torch, watched the fitting with bated breath as Calstar settled back into the water.

All seemed good. For just a moment. Then I spotted the slightest bead of moisture, gradually swelling, around the seam between the housing and the hull.

It was but the slightest weep. In truth, it could well have been doing this all through the previous year and we might not have noticed. She's a very dry boat, but there's always a bit of wet to mop out of the the bilges. But the idea of putting her back on her berth now we knew the integrity of the seal was definitely compromised?

It wasn't ever really a serious proposition. 

So she was lifted back out and returned to the yard. The log is an old AutoHelm Bidata ST30, the same age as the boat. Dad wasn't happy with removing and refitting a 40 year old piece of plastic, but Sam from the Marina boatyard was able to source a Raymarine ST40 transducer. 

As I understand it, AutoHelm was the brand name used by the original UK company Raymarine until they were brought out by a US company called Raytheon. Then there was another buyout and Raymarine became independent again, and reverted to the Raymarine brand.

In any case, the upshot is that the Raymarine ST40 speed transducer has the same footprint as the old Autohelm ST30, and uses the same Seatalk1 data, so remains compatible with our existing display. And I've received an email from Sam this morning to confirm that the log has been fitted and the lift booked for the re-launch.

So come Monday 0900hrs, we go again.