Boom Height

[Walter Pearson]

The black band on my E27 mast has been useful to obtain a rough visual correlation to the position of main halyard, but since my gooseneck is free to slide within the mast luff groove, it doesn't necessarily have a specific relationship to the boom. I am going to secure a different gooseneck design to the mast and wonder if there is a relationship that is more suitable than another. Does the black band typically line up with the centerline of the boom extrusion? With the foot of the sail? Or is 'typical' just not a nautical term?

 

[marcusn]

Thanks for asking! I have the same question.

I was fortunate this fall, and found an affordable 1975 e27! (always a long distance admirer of Ericson boats). Mine also has a black tape mark on the mast, and a gooseneck that slides freely. I figure the main uphaul would hold the mast up when the mainsail is hoisted, but wonder what would hold the mast end of the boom up if the sail is down (ie. at anchor).

 

[Loren Beach]

Black Band

Here is a thread I found with some searching and getting a bunch of results from the words -- 'black band'.
http://www.ericsonyachts.org/infoexchange/showthread.php?t=5042&referrerid=28

Looks kinda sorta related...

Cheers,
Loren

 

[Walter Pearson]

Loren: Thanks for the link. That gives me a good reference point. As far as I know, my mainsail is not oversized, so putting either the boom centerline or the foot groove at the band height would work.

Marcusn: As far as holding up the aft end of the boom, my E27 has a snap hook on a short wire rope that attaches to the junction of the split backstays. This hook can be attached to a hole in a small plate that is attached to the boom end. I still use this for securing the boom when in the slip or at anchor. I found it somewhat inconvenient and sometimes dangerous to use while underway because of my precarious stance to reach it and because the boom did not always cooperate and had to be kept amidship when it really didn't want to. I added a topping lift that was secured at the top of the mast. I have now added a rigid vang which is not suited for a boom that rotates and/or slides up and down at the mast, so that leads me to a new gooseneck arrangement.

 

[Seth]

Black band

To correctly locate the lowwer black band which will indicate the tack location you measure the distance of the P measurement from the BOTTOM of the upper back band to the TOP of the lower band-and the TOP of the lower band must be even with the TOP of the boom groove-NOT the centerline of the boom...

Put differently, the distance you are looking for equals the P measurement and is defined between the top of the bottom band and the bottom of the top band..
Hope this helps,
S

 

[Walter Pearson]

Sorry - I misread earlier post and expounded on the wrong end of the boom in previous reply. For the mast end, my sliding gooseneck is kept from dropping down by a track stop that has a round slide (e.g. Davis 2350, West 108332). Originally, there were also track stops to keep the sail slugs from coming out of the luff slot, but have since made plates to keep them in the groove.

Seth: Thanks for further clarification. I'll forget about using the center of the boom as reference for a fixed location. I don't remember ever seeing the upper band on the mast. Being the most exposed, it probably faded away long ago. (There's not really much showing on the bottom one either.) I'm a little confused when "P" takes on a location aspect in addition to its length. Does that mean you should never raise the main such that the tack would go above the top of the lower stripe? But having the tack below that stripe is OK - as long as the head is also below the hypothetical upper band by the same amount? This all seems somewhat cumbersome with a system where the luff tension is adjusted by downward forces at the boom.

 

[Seth]

I hear you

You are right. On most boats the gooseneck is fixed, and it is at a point where if you extended a line even with the top of the boom to the mast you would have the location for the top of a lower band, and this (top of the band) is supposed to be located the P distance down from the bottom of the upper band(if there is one)..With a fixed gooseneck you can use a cunningham (like most boats) to adjust luff tension...

What really matters is that you contain the mainsail luff in a distance not exceeding the P measurement (for racing).

Raise the mainsail up so that the head is as high as you can go without fouling the halyard shackle in the halyard sheave, and checking to see if the leech of main is clearing the backstay. This is your "full hoist location". Then place a piece of black tape with the bottom of the tape even with the headboard at this level. Measure down the distance of your P measurement, and place another piece of tape with the top side at this location.

This is the area between which the head and tack of the main should stay (this only matters for racing). If you are racing, you cannot adjust the gooseneck below this point. If cruising, have at it.

But by locating the upper band as explained, you are getting the head of the sail up as high as it can be without fouling the sheave or backstay, and that is what you want for any boat-then the only issue is how you adjust luff tension down low. As long as you are not racing you can do as you please with the goosneck. An added bennie is that this will keep the boom as high as possible and reduce the dreaded headknocking effect.

Does this help? Feel free to contact me directly by PM or email if you want to go into specifics-I'm happy to give you a phone # to speed things up. In fact here it is-I give it away anyway to the group for anyone who wants to chat...312-735-6360.

Good luck!

S

 

[Walter Pearson]

Thanks - that does help. I think I have enough information to get going on making some parts. I have added a winch for the main halyard so I'm gradually getting away from the old system. I don't (officially) race, but I would like to make sure a future owner doesn't have to redo things if he/she wants to race for real.