Mast Exit Plates

[jssailem]

Because of the way a spinnaker halyard moves about and can be chafed on the mast entry I elected to run it on the outside of the mast. Not an issue with noise. Run the line to the bow and tie off on the deck away from mast.

 

[Ron20324]

On this site, a harken bullet 089, 07430. or maybe a289,23288?

 

[Scott T-Bird]

No, not the usual (with the Ronstan exit plates) and that's my point... There are no corners, you make a narrow oval slot for the halyard to pass through. Let me clarify that the Rostan exit plates are only for the line entering the mast at the bottom, there is no turning block for exiting the mast at the top in the case of the Spin halyard. In those cases I like the Harken thru deck blocks. The medium size can take a 5/16 line without rubbing and the cut slot is significantly smaller than most other blocks. I'll have to snap a pic at home because I cant remember the model number on that one, but it does have a cover plate.

The spin halyard uses an exit plate at the bottom and top also because it is a fair lead at the top of the mast to the exterior block that is hung from the crane. The only place where the exit block is needed is for the spin topping lift. I see the Harken thru-deck blocks and there is a 29 mm block for 8 mm line (5/16") but the cut-out is still wider (at 3/4") than the Kenyon (at 9/16") - length is the same at 1-3/4". The cover plate of the Harken does look cleaner, but the mounting holes are above and below the cutout, whereas the mounting holes of the Kenyon are to the side (on the flanges). I don't know if there is a significant difference in that regard. The Kenyon block is slightly greater in diameter, which would seem to be an advantage. I already have the part, and it is made specifically for my application (opposed to the Harken which is made for a deck), so I think I will still go with the Kenyon block.

 

[Scott T-Bird]

Because of the way a spinnaker halyard moves about and can be chafed on the mast entry I elected to run it on the outside of the mast. Not an issue with noise. Run the line to the bow and tie off on the deck away from mast.

I have the spin halyard and a 2nd jib halyard on the outside and don't like it that way. (Previously, I used the 2nd halyard as the topping lift) With infrequent use, I think chafe will not be such a problem. The warp speed halyards I use have durable covers. I like the clean look of internal halyards and lifts, thus the reason for the project.

 

[Jackdaw]

Every good rigger will tell you that if you stagger the holes and make GOOD cuts, there is no issue with weakening the mast at all.

To make the cuts, use a big bit or a small hole saw the width of the slot to make holess that match the curved ends on each end. With a jigsaw on slow, use a sharp aluminum cutting blade to cut the straight sides. Avoid at all costs nicks that run straight into the spar. Use a file to remove ALL burrs.

BlueJ's spar must have at least 10 halyard exits (not including lights, spreaders, and stays) and there're the last thing I'd every worry about.

 

[Jackdaw]

PS - the good riggers will also tell you that the best exit plate is none at all, a perfectly faired hole made smooth on the inside as well by filing and sanding. The 367 mast came like this; clean, simple, no corrosion and no extra parts. Takes time but worth it.

 

[CloudDiver]

PS - the good riggers will also tell you that the best exit plate is none at all, a perfectly faired hole made smooth on the inside as well by filing and sanding. The 367 mast came like this; clean, simple, no corrosion and no extra parts. Takes time but worth it.

Great point... I've seen this myself actually. I love metalwork so I took a good hard look at it and imagined how it was done. A nicely cut oval and then using two solid steel rods in tandem you can put a slight outward flare on the upper half while creating a slight depression in the lower half. Some fine files and sandpaper make everything butter smooth.

 

[Crazy Dave Condon]

Jackdaw, you are correct about filing. I use to cut exits in smaller masts and some on the larger masts. However, I use to bevel the upper portion of the slot upwards and the filed smooth making the edges dull, not sharp. That way it made a much cleaner exit. It took more time but it worked.