Mast Exit Plates

[Scott T-Bird]

One of my winter projects is to install 4 additional exit plates to supplement the 2 exit plates that were originally installed. I'll have a total of 6 exit plates to serve internal halyards for 4 masthead sheaves, 1 spinnaker block and 1 spinnaker topping lift. The mast section is Kenyon MORC 4060.
My question is how to space the exit plates so as not to cause any structural failure of the mast. The only reference that I can find is from Selden. Their instructions say that on each side of the mast, exit plates must have 12" (30 cm) vertical separation. I'm assuming that I can offset the alignment slightly, rather than placing them in a vertical line (3 on each side). They seem to indicate that you can pair the exit plates on both sides of the mast, meaning that it is ok to have a hole at the same location on each side. I suppose this sounds like a reasonable guideline. The only reference I can find for Kenyon masts is thru Rig-Rite, Inc. Aside from getting any guidance here, I will resort to their recommendations over the phone, assuming that they will be helpful.

 

[Gunni]

I have perhaps 5 slots in my mast. They should not be in vertical alignment because you want a fairlead to a a cleat, clutch or winch. Not placing them at the same vertical location is also a good idea and presents no problems, and some opportunities - example: My mainsail halyard exits the mast well off the deck, this allows ample room to reach, grip and sweat the halyard up while another crew member winches from the cockpit. Makes for a quick hoist. tie a figure eight in your bitter end...

 

[jssailem]

Scott.
Fred Cook (of Schaefer Marine) is restoring a Cal40 to Bristol condition. Intent is to race and win with this historic boat. The mast is being designed and built by one of the experts on the West Coast. Ballenger Spars. In this YouTube vid Fred discusses the elements of his new mast. Included is info about how Ballenger aligns his exit plates for efficiency and maintenance of strength in the spar.

 

[Jackdaw]

12 inch vert separation is good. 6 inch stagger port/starboard. Horizontal alignment over the deck turning blocks. Avoid any exits in line with the boom. Halyard exits (in particular spin) as high as possible to facilitate jumping.

 

[Scott T-Bird]

12 inch vert separation is good. 6 inch stagger port/starboard. Horizontal alignment over the deck turning blocks. Avoid any exits in line with the boom. Halyard exits (in particular spin) as high as possible to facilitate jumping.

Thanks, that sounds right with regard to staggering the port/stbd sides. I know that the existing openings are staggered, but until I measure, I don't know the distance for sure. I'll have to base my pattern off the original 2 openings.

 

[shemandr]

I'll second the advice about making them high enough for jumping. I sail on a number of OPB's and am annoyed by exit plates which are too low to get my full body into. I'm 6' with longish arms and 8' off the deck isn't too high. 10' would be better.

 

[Jackdaw]

Oh, everything else can be on ether side, but SPIN 1 HAS to be on starboard.

 

[vhoisington]

OK - I'll bite

I'm actually planning lines led aft on my 40 year old Islander, Why does SPIN 1 have to be on Starboard?

As I've thought my plan out I'll have 8 lines:
- Halyards - Main, Jib, Staysail, Spinnaker,
- Reef 1 & 2 (should include room for Reef 3)
- Vang
- Mainsheet - The traveler is located end boom so may run this from behind (it is a center cockpit boat)

My halyards are currently running external so I can move them to either side
I'm thinking of the following arrangement
Port - Jib, Staysail halyards, Reef 1 & 2: run through a quad deck organizer, dedicated Winch
Stbd - Main, Spin Halyard, Vang, Mainsheet: first 3 through a triple Deck organizer, Mainsheet with a dedicated Cam cleat, unless I decide to manage the main from behind ( may be simpler to handle with less line in the cockpit)

My big question for this plan, besides proper location of the halyards per Jackdaw's comment above, is how to run the lines from the mast. My boat is a pilot house with the mast stepped in front of the house so, using a base plate as an anchor is not viable, Do I just set fixed blocks on the mast or should I devise some sort of mast ring at pilot house level?

Thoughts?

 

[Jackdaw]

Spin on starboard.

If you ever race the boat, 90% of your rounding will be leaving any mark to PORT. This is done deliberately in racing so boats naturally approaching a mark on starboard have rights.

The boat will be heeling to port, and someone jumping at the mast will be much happier standing on the high/flat side.

If you never race or have a very heavy boat, not so much an issue. But if there is no other downside, why not do it right? ;^)

 

[vhoisington]

Thanks Jackdaw!! Makes perfect sense, I don't race (much) but your logic makes perfect sense. I'll keep that in mind as I plan out my deck arrangement.

Happy Holidays to all!!

 

[shemandr]

I've been told the traditional, and proper position for main and jib halyards is main on Starboard and jib on Port. It doesn't matter except that a convention is useful for crew to be able to go to the desired halyard quickly.

 

[Crazy Dave Condon]

Scott T-bird;
Kenyon use to be located in California along time ago. It merged with Isomat to become Kenyon Isomat which then moved to Charlotte, NC. In the 90's, Z spar bought Kenyon Isomat. Kenyon Isomat laid off everyone while Z Spar left Gainesville, FL closing down that plant and moving into Kenyon Isomat facility moving only four people. That of course delayed masts to many manufacturers to include Hunter and others. Without actually going into why Z Spar left the country, that left many to include dealers like me in the lurch with boats without masts. Selden came along and started building masts for Hunter in South Charleston, SC and eventually for others. The personnel from Kenyon Isomat then reopened in the old Charlotte, NC facility under Charleston Spar but later became Sparcraft. You may still see parts listed under the Sparcraft website but suggest that you go to Rig Rite who apparerntly has an affiliation with Sparcraft and can help you with the parts if you can send photos and detailed information unless you can find another source. I do not believer the forum store can help you.

As for Z Spar, that name will never come back into this country. It did reappear under the name of US Spars located in the same facility as Z Spar outside of Gainesville, Fl. My understanding that the same two men in France who owned Z Spar also own US Spars. Not sure this information will be handy but hope it will.

Crazy Dave Condon
Happy New year to all.

Once a friend of mine whose father served in the British Army told me that his father was captured in WW II in I believe Arnheim (not sure of spelling) when they could not capture that bridge which a movie " A Bridge too Far" was made. He said "so close, yet so far". Relationships can be like that.

 

[Scott T-Bird]

Hi Dave,
I've purchased the parts from Rig Rite, Inc. I've often wondered why they seem to be the only outlet for parts that fit the various Kenyon mast profiles. I've also wondered what is the correct part to use at the top of the mast where the spinnaker halyard enters the mast from the crane. I've purchased an "Exit Plate" to install upside down, because I can't find any other part specifically for this purpose. Is there a better way to do it? The halyard comes from an external block which is hung from the crane.

 

[Jackdaw]

Spar vendors are really geared to sell masts to the OEM boat builders on an industrial basis. They are not really set up to sell spare parts one-off to end users with 30 year old masts.

Some will still do it (USspars) but signal their displeasure with a $20 minimum shipping charge.

Rig Rite is better equipped to do that, and the spar vendors are happy to sell though them.

 

[Jackdaw]

Small opening mast exist plates are cleaner at the masttop and limit water in the mast. Don't use them at the bottom as jumping the halyard pulls it with extra friction, and if you need to re-run a halyard you'll NEVER fish it into the tiny hole.

 

[CloudDiver]

If @Scott T-Bird already bought the parts it may be too late for my .02, but... Since I'm switching to internal halyards also, and with a smaller boat I have a smaller spar with thinner wall, mast exit boxes w/sheaves scare the crap out of me. I have seen masts on 30ft boats fold where the big square cut was made for the box. I like Ronstan exit plates; inexpensive, easy to install, only one fastener, smooth fairlead, and easy to remove if you get corrosion between the dissimilar metals... but most notable is that cut requirement is a very narrow slot (two holes and a dremel metal cut wheel, clean up with a fine file). The smallest size takes up to a 3/8" halyard, the medium up to 1/2 inch.
Echoing posts above, don't compromise spar strength by staggering exit cuts horizontally and vertically.

http://www.ronstan.com/marine/range.asp?RnID=109

 

[Ron20324]

[QUOTE="CloudDiver,... mast exit boxes w/sheaves scare the crap out of me. I have seen masts on 30ft boats fold where the big square cut was made for the box. ...[/QUOTE]

The usual... Start out with round holes where the corners will be.

 

[Scott T-Bird]

I plan on installing an exit block for the spin topping lift on the centerline at the front of the mast somewhere between the spreaders and the upper shroud (3/4 of the way up the masthead rig). The block I have purchased is K-11110A-1, which has the curved flange for this application. The cut-out is 1-3/4" x 9/16" wide, which is the smallest I can find for a line that is anticipated to be just 8 mm diameter. The only thing I don't like about it is there is no hood over the opening.
http://www.rigrite.com/Spars/Kenyon_Spars/Kenyon_Parts/K_exit_block.html
I'll also have to shove the pvc wire conduit out of the way and re-fasten it at this location, as it is also attached at the front centerline of the mast.
I suppose that over-stressing the backstay with the adjuster could be a feasible danger if the block causes weakness in tensioning the leading edge of the mast.

 

[CloudDiver]

[QUOTE="CloudDiver,... mast exit boxes w/sheaves scare the crap out of me. I have seen masts on 30ft boats fold where the big square cut was made for the box. ...

The usual... Start out with round holes where the corners will be.[/QUOTE]
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.

 

[Ron20324]

I plan on installing an exit block for the spin topping lift on the centerline at the front of the mast somewhere between the spreaders and the upper shroud (3/4 of the way up the masthead rig). ....

Maybe a bigger hole, but have you looked at the blocks with and upper and lower sheaves in the fixture? I'll try to find the #.