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Mast fittings.

Author rob baker
Registered
#1 | Posted: 17 Sep 2018 20:19 
Been searching for various items that may be of service to us, found some clamps of various diameter including 65mm which is diameter of most Minisail masts, these clamps can be used for boom rests, rowlock will sit on top enabling downhaul and kicker to be more efficient.

https://www.ebay.co.uk/itm/Clamp-Collar-Single-Split-3mm-To-100mm-Inside-Diameter-Sha ft-Collar-Clamp-Type/302159916573?hash=item465a226e1d:m:mWiCz1_tA3Pa9V6s5zZemcg

Author RonnyDG
Registered
#2 | Posted: 19 Sep 2018 16:35 
I didn't know these were made in XXL size, I have some in 4 and 6mm size that fit my wood drills. A nice find, though rust might be an issue when used on a boat. A nylon version would be perfect, i'd like four please.
The item reminds me of the mast-collars you made for your Sprint, these are recommendable for any Minisail.

Author rob baker
Registered
#3 | Posted: 19 Sep 2018 19:47 
I am also in talks with a aluminium tube company, just trying to find exact grade of ally required.
Collar clamp was just to give people an idea of what sort of item will do a job, they are probably available in aluminium and nylon.
I don't know anything about 3D printers ? perhaps collars could be made that way, would they be strong enough ?
I hope to find a range of products we can use, will post more details.

Author John Banks
Registered
#4 | Posted: 20 Sep 2018 17:24 
Hi Rob
This is a good find and if in alloy or plastic / nylon would be great. I don't know much about 3D printing except that I would have thought it easily possible and if cheap enough, it would only need to last a season.
What I have done is to make a lashing on the mast and cover in black tape to keep it in place for the boom rests / rowlock. Something more secure and less Heath Robinson would be great.
Cheers
John

Author rob baker
Registered
#5 | Posted: 20 Sep 2018 19:12 
These are the grades for masts,

Aluminium 5000 series alloys (5083, 5086)
Aluminium 6000 series alloys (6061T5/T6, 6082T5/T6)

however, some masts are just aluminium, not heat treated at all.

Author rob baker
Registered
#6 | Posted: 20 Sep 2018 22:24 
Found this place, they will 3D print in a variety of materials, also stock split collars in stainless steel.

https://shaft-collars-couplings.staffordmfg.com/category/round-bore-shaft-collars

Author Notoverthehill
Registered
#7 | Posted: 22 Sep 2018 23:30 
rob baker
The simple answer to boom support as always used in the class is a strop, thin wire or non stretch cord fitting closely round the top section and sitting tight on the bottom one so it doesn't slide down. the bottom loop fits over the boom at the appropriate height. Light, cheap and adjustable ( cord version ). Tom

Author Notoverthehill
Registered
#8 | Posted: 22 Sep 2018 23:51 
I have one boom support strop in flexy ( 9 strand ? ) stainless wire about 2mm diameter, like that used for dinghy halyards. The top loop has clear poly/plastic tube sleeved over it to save the anodizing on the mast. a Talurit splice closes the loop ( about 60mm diameter, just enough to go over the top section. I have a tiny stainless wire clamp for the bottom loop, so it's adjustable.. Rope ones are easy to make, a bowline at the top and bottom .The strop stops the sail being pulled below the measurement band or over stretched by the kicker or Cunningham, in fact it allows the Cunningham hole to pull the luff/front only of the sail down against the fixed boom height. Tom

Author rob baker
Registered
#9 | Posted: 23 Sep 2018 20:53 
Tom,
I am not suggesting these fittings for all Minisails, the early wooden ones should be left alone, however GRP boats and most certainly mk2 Sprint will not be historically damaged by this mod, which in effect offers a simpler boom rest rather than having to tie bits of string, which have a remarkable propensity to undo themselves.

Author SteveW
Registered
#10 | Posted: 16 Oct 2018 16:32 
If anyone would like mast or boom plugs turned up in Acetal then
please get in touch. I have made them for each of my spars, they are a
snug push fit and I haven't needed any sort if mechanical fixing to
hold them in. I can drill the forward boom one for a standard RWO
rowlock/gooseneck as required.
I don't want any money for them (I have materials and they only take
15 mins or so) but I won't object if you want to contribute to postage
:-)
By the way, they only come in black!
Cheers.
Steve.

Author Notoverthehill
Registered
#11 | Posted: 16 Oct 2018 21:34 
Steve. , I am down to my last mast plug from the very reasonable ( Wolverhampton ? ) Dinghy Bits or some such name, who also seem to be low on stocks, a mast foot plug would be very useful. I have to grind the ones I buy as they sometimes are a tad oversize for the mast pot. I have at least one home made lower section requiring a plug. I have length of round hardwood stair rail which fits my boom sections nicely if anyone wants to try a local source, not as durable as yours Steve but they do the job.

Rob,
I admire your ingenuity and inventiveness and craftsmanship in making excellent fittings. However as thousands of Minisailors used the cord or wire strop as standard to prevent undue loading on the luff incidentally and keep the boom above the measurement band and allow the cunningham to operate it is not unproven. The strop in non stretch line weighs next to nothing and and bowlines do not come undone under load. As our 1976 Minisail year book contributor from Newcastle confirmed, in another post recently. It also allows adjustment for slightly different luff lengths if one has more than one sail. Each to his own, but for me it's important not to invent more complex solutions to simple needs.
Cheers,
Tom

Author SteveW
Registered
#12 | Posted: 17 Oct 2018 19:35 
Hi Rob
Can you measure the internal diameter of the mast you want a foot for - Just to make sure I get it right! I will knock you one up in the next week or so if you want to send me your address - maybe via email rather than on here - its steveATgravelpitfarmDOTcoDOTuk
Cheers.
S

Author rob baker
Registered
#13 | Posted: 17 Oct 2018 22:14 
Hi Steve,
Away for a few weeks, will message when I am back
Thanks
Rob

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