Saturday, March 5, 2011

Mast Compression One

Bottle jack action
"Ooh. That's a Hurley 22?"

Say yes.

"Scott had a Hurley 22 back when we first met. Then there were the kids so we bought Jenbenbav. But Hurley's are such lovely boats. We had so much fun back then!"

Smile.

"Of course Jenben is very comfortable. Still, sometimes I miss the old Hurley. I think we enjoyed sailing more then, didn't we Scott?"

Feign incomprehension. Then, through the course of Scott's tale - involving crab pots, Chapman's Pool, an omelette and fog - allow appreciation and amazement to educate your wind-burnt mug. All you want is an invite into their shore-powered warmth and, perhaps, a tot of their malts.

But they're not wrong. Hurleys are lovely boats. Mine suffers from mast compression.




The bermudan rig relies on a tension for performance. The stays and shrouds pull the mast downwards. On some boats, the mast starts at the keel and pokes up through the deck. On most others there's a solid kingpost between the the keel and the underside of the deck-stepped mast. With Kemara's ilk, there's nothing but thin air under the mast.

So Hurley 22s are prone to mast compression: under rigging load the deck sags, just aft of the mast step. On Kemara it didn't look fatal: the deck hadn't cracked, I didn't think the mast was in danger of crashing down into the hideaway toilet directly beneath it. But the rig wouldn't tension. Beating into a stiff breeze she carried unmanageable weather helm and pointed about as well a red setter on heat.

Roger and I had already made several attempts at a fix.

I'd laminated up a formidable beam and bolted it in place just forward of the bulkhead, around half a meter aft of the mast. We put a stainless plate between the underside of the mast step and the beam and hoped this would take the strain aft and out to the edge of the coachroof. But we skimped on the thickness of the stainless plate. It bent, the deck still buckled and, worse, the bolt holes leaked.

The following year I ordered up a serious 8mm stainless plate, with the long edges bent down for additional strength. I should have realised that 8mm was overdoing it when the engineering company started scratching grey heads over the size of press needed to fold those edges. But they did what was asked and a terrifying lump of metal arrived at my workplace.

Down at the Exeter Canal Basin, the weekend before we were due to get craned in, I found the folly of my never-too-strong ways. Those chunky bent down edges would need cutting off where the plate had to sit atop the beam. And that would take a plasma cutter. Which I don't own. And B&Q don't sell. We stepped the mast without it, and again sailed the season with a sagging deck and leaky bolt holes.



This time last year, the boat now mine, I was determined to lick the problem. Precision Profiles of Bristol did me another 8mm plate, without the bent down edges. It still would take an icebreaker to bend. With a couple of weeks to spare before the convoy went down the canal I set about installing it.

I had decided to epoxy the beam and plate to the underside of the coach roof: no more leaky bolts. To do this I had to find something solid on which to glue. The interior ceiling of Kemara's cabin is moulded out of thin fibreglass, with a blueish textured finish. Tapping it I could hear solid patch running aft from the mast to the companionway. So I nervously drilled and chiselled the thin glass away.

Crack of doom
Underneath was a mess of water-stained glass-over-wood, shot with ancient holes. Just aft of the mast it had cracked, precisely where the deck was sagging. I put 40 grit on the angle grinder and proceeded to make a nice flat surface.

The result was cleaner, but disconcerting. The angle grinder had torn away a chunk of glass on the starboard side of the crack, exposing a wet brown substrate. I pushed a chisel in. Dark lumps of cheddar-ish matter fell away.

The Hurley 22 has a three quarter inch mahogany plank running from the front of the coachroof aft to the companion way. It's encased in a (typically) hefty amount of fibreglass. Six bolts run through it to hold the mast step in place.

Some past someone moved Kemara's mast forward a couple of inches, probably in attempt to balance the sails and reduce weather helm. So instead of six holes through the mahogany and glass, I had twelve. The aft two had been repurposed: the VHF antennae and navlight wiring now ran through them, providing an easy ingress for rain, spray and the green salty sea. The weakened wood has rotted; that terrible crack now joined the holes.

Gas lit solace
Fibreglass boats aren't supposed to rot, I cried at the startled quay. Then I did the only sensible thing: retreat to the Welcome. There, pint of Ferryman in hand, was the Captain, owner of the oldest wooden sailboat on the Exe. He was inured to rot. So I asked him what to do.

"You will never enjoy sailing a boat you do not trust."

OK, quite possibly true. But do I just epoxy the stainless over the crack and pretend I haven't probed it, smelt the cheese? I bought him one.

"There are people who sail boats. There are people who mend boats. People who mend boats don't do much sailing."

Ah. I should bodge it. Another pint.

"You will never enjoy sailing a boat you do not trust."

Shit.

Just how bad was that rot? Back onboard I drilled some exploratory holes, first aft along the mahogany plank, then into the stiffeners that crossed it. Except for the aftmost 60cm, the plank was rotten. And, when I drilled into the stiffener black water sprayed off the bit, blinding me.

That decided it. I couldn't live with a fetid aquarium in my coachroof. I fired up the angle grinder. And became one of those people who mend boats, not sail them.