Drilling new holes in the mast

[Seajet]

Dan,

I've had a quick look at the barton & Ronstan websites but they're very vague, dunno if they have the sort of thing I'm on about or not.

Here is a pic ; best one I could find, the double ball bearing sheaves in the mast are my point, with these one could tolerate an upwards pull - but it woud still need to be at a roughly suitable angle !

I think you could use normal single - hopefully ball bearing - sheaves well above the deck, pulling & swigging down to staghorn cleats just above the foredeck ?

View attachment 57815

 

[Greenheart]

I like the pic Andy, and those blocks would certainly allow pulling from a variety of angles...

...but how am I to accommodate a pair of them, in the tiny flared section of the mast track? That's my difficulty.

Compared with that, the idea of refurbishing the present system looks easy.

I'm off down there now, back on-air late tonight. Thanks all. :encouragement:

 

[Seajet]

Dan,

hope your trip is fruitful; I was thinking of fitting new sheaves higher up, as I mentioned they could be above foredeck level and pulling down around cleats for swigging - no reason they couldn't be staggered, and wouldn't have to be double, just as well as I can't find the source where I got those from, and the ball bearing organisers are somewhat amazingly unavailable now too !

 

[Greenheart]

Not a wasted evening. Before I got to the shed, I'd decided to rip out the old exit box. It was too far-gone; even the casing is flaking and I doubt a new sheave would run smoothly against its inside walls. I drilled out the bolts and reached for the mole-grips...

...and again I reflected dolefully that I'll be unlikely to find a replacement of exactly that size...(the rod inside the sheaves was immovable - not jammed by corrosion, but fixed by design...so just replacing the sheaves didn't look like an option.)

...so I started looking for anything which might substitute. Andy...here are what I call 'hollow-spindle' mini-blocks...alas no bearings...

...but near enough to the same breadth that I needed...and the hollow spindle means the block could be bolted securely in place.

So, I drilled a hole in the right spot on the mast and packed out the slack with washers on the stainless M5 bolt...didn't tighten it yet...

Of course, the M5 bolt may or may not be strong enough for the purpose; but I can use the blocks' framing to wire them to the foot of the mast for extra strength. Will I need some Duralac to separate the stainless and alloy in close contact?

Considering I didn't buy anything, I reckon it could look worse. Now I can finally start thinking about where to re-site the cleats.

 

[Kelpie]

Well done, looks like a good wee fix. I wouldn't worry about that M5 bolt shearing off. You seem to have a bit of dyneema tying the blocks down as well so that should be belt and braces.
The only improvement I would suggest (other than cleat position, obviously) would be to find blocks with wider diameter sheaves, to reduce friction.

 

[Greenheart]

Thanks Kelpie. I reckon it will be okay. Much better than the old exit-box anyway.

And hence, at great length, I arrived at the reason for starting the thread...drilling holes in the mast to re-site the cleats. Oh my lord, a 5mm hole looks massive in a dinghy mast...

But that was the size of the rivets I'd bought. I deliberately staggered the siting of the new cleats to prevent more holes than necessary appearing in the same area of the mast...

...and a damned difficult thing it was, to pop monel rivets using the standard tool, having forgotten the extension-arms I'd made...

...but I did achieve the new locations for the cleats, visible in the photo below. The pink arrows indicate the old cleat rivet holes...the cleats were a pain to use, down there.

Technically that's the end of the story thank God, but in my toolbox, nothing's ever that simple...not all the monel rivets 'popped' completely, so the cleats aren't rock-solid-rigid...

...and I forgot to use Duralac so I've put monel rivets in an alloy mast...but, can I now epoxy over the rivets to prevent them getting wet and reacting galvanically with the mast?

Much worse, one mandril broke off short, leaving a stump which I could only remove by grinding it out, and in so doing, I managed to grind away some of the cleat's ribbing...

...so, I may have to drill some of the rivets out anyway to replace the worn cleat, which'll give me the chance to apply Duralac.

I wonder what'll happen with that stump of steel mandril touching the monel rivet, also uninsulated from the alloy mast...I'll go back and find the whole shed has burned down.