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I've seen that one owner of the same model boat as ours bolted a plate to the mast head then added a couple of blocks at the end of the plate for the flying the spinnaker and sock. I'm guessing that was done so the spinnaker halyard is out front of the forestay which should avoid chaffing. I'm not to fond of drilling holes in the boat so what I'm thinking is to epoxy an aluminum plate on top of the mast head. Then add a block or two at the end of the plate for the halyard. Of course the paint of the top of the mast head would be removed, metal roughed up then JB Weld mixed and applied. Then paint it.
Is this a good plan? Maybe I'm overly concerned about chaffing and this modification is not needed? The boat does have two jib halyards available.
Methacrylates are used for bonding structural aluminum... ie mainly sheet to angle or square tubing. Even if you use the methacrylate for bonding I would suggest that you also tap the mast and bolt the plate with stainless bolts coated with tef gel. No such thing as too strong.
" How much actual bonding area would there be? " The plate I'm thinking about would be 2 inch wide and the top of the mast head is about 14 inches long so that is 28 square inches.
" Where are you going to put in " Deale, Maryland or points south. We have our house up for sale so we can move to that area.
That's a pretty good bonding area. Once cured thoroughly, wack it hard with a hammer; if it doesn't break it might be okay. I would rather have at least a couple of modest sized bolts or rivets in addition to the epoxy...it isn't like there is a risk of sinking the boat because of the bored holes.
This makes me nervous. You can get big loads on the spinnaker block and a failure would surely come at the worst possible time. I'd go with the bolts as worked for others (sounds like your mast may be down, so drilling & tapping should be easy). Also, using a jib halyard for the spinnaker will likely give you the wrong geometry and lead to fouling the halyard(s) on the headstay.
??? make the plate a clamp with ear brackets welded on leading edge to take pins for sheaves. If main halyard is masthead and internal maybe longer sheave pin to mate with the wrap around clamp (lower ears).
Good idea, like the idea of clamping the plate using a longer pin. Have to look at the present arrangement to see if it is possible. And check with my welder about welding aluminum. He does outstanding work on stainless.
Yes the mast is down since the boat is in the driveway on its trailer.
So make it aSS strap, clamp around the mast above the halyard pin. (so it can't slid down.) Insulate from al. Front ears, bend up frm heavier strap rivet/,weld.
I've seen that one owner of the same model boat as ours bolted a plate to the mast head then added a couple of blocks at the end of the plate for the flying the spinnaker and sock. I'm guessing that was done so the spinnaker halyard is out front of the forestay which should avoid chaffing. I'm not to fond of drilling holes in the boat so what I'm thinking is to epoxy an aluminum plate on top of the mast head. Then add a block or two at the end of the plate for the halyard. Of course the paint of the top of the mast head would be removed, metal roughed up then JB Weld mixed and applied. Then paint it.
Is this a good plan? Maybe I'm overly concerned about chaffing and this modification is not needed? The boat does have two jib halyards available.
I think you over estimate the strength of JB Weld! That is absolutely the wrong application for that stuff. The loads on a spinnaker halyard can be pretty high. If the epoxies area proves too weak you will have a mess on your hands.
Why are you afraid to bolt anything to your mast? Bolting a block is not going to compromise the strength of the mast at all, but will give you a spin halyard you can have confidence in.
If you are not confident drilling and tapping your mast, perhaps you should enlist your local rigger to help.
Captain Len proposed making a bracket held on using the sheave clevis pins. I took a look at the mast head today and instead of holding the bracket on using the sheave pins, the forestay and backstay cleavis pins would work better. Also I thought the bracket could be fabricated using either a channel or angle bracket as a start, then overbored threw a left handed monky wrench into the works. A less than $50.00 solution from Catalina Direct, simple elegant and no hole drilling required to mount it. While that particular Spinnaker Crane won't fit (too narrow for starters) it does provide a starting concept for my fabricator. And I will contact Bob at Nor'sea about the factory option.
Don't reinvent the wheel. Drill and tap the plate into the masthead, been done that way since forever and works. Use caulk between the plate masthead to seal out moisture and any chance of corrosion. SS spinnaker cranes with welded loop eyes sticking out horizontally usually end up bending from the downforce. A flat plate with reinforcing ridge welded to the plate and 'U' bolts for block should prevent this. Here's cast one that has the reinforcing ribs. Z-Spar Masthead Spinnaker Bails
Hi, my name is Shipper Jer and I have trypophobia. (Not really, drilling holes in our boat is the very last thing I want to do)
I do appreciate the recommendation that I drill and tap the masthead then mount a flat plate for the spinnaker crane.
I'm going to mount the crane using the existing holes that are there for the sheave and stay clevis pins.
So to wrap this thread up I now have a spinnaker crane. My local welder fabricated one using stainless steel plate. I drilled two holes in the U shaped bracket that line up with the existing holes in the mast head. The crane is held on using longer clevis pins. Those holes are for the forestay clevis pin and a hole that wasn't being used. Today I hoisted the asymmetric along with a chute scoop. AWESOME! I'm really happy with the setup and I didn't have to drill holes in the boat. And as a side benefit the crane provided a mounting location for our new masthead tricolor.
I have been envisioning you hoisting yourself up a swaying mast, in cool, possibly rainy weather, taking measurements and trial fitting various pins and parts, probably many times to get it 'just right'. But instead you lowered the mast and pulled up a stool to make yourself comfortable while you installed the aforementioned pieces. Is that about right Skipper Jer?
Pretty much got it right. I did have to lean over the bow rail a bit. Sometimes I would just stop work on it to gaze out over beautiful hills and river views while my wife would pass me a cold beer.
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