Thanks Dave. This helps me a lot to understand the issues. Mine still had the ¼” main halyard & 5/16” jib halyard. That confused me and I concluded that one was improperly replace at some time. This contributed to my buying one set of ¼” and one set of 5/16” halyards. So now I have three sets, counting the originals, none of which are long enough to replace the wire portion. Oh well. I guess you can’t have too much line, I hope. Sent from Mail for Windows 10 From: Dave Scobie Sent: Monday, June 29, 2020 8:39 PM To: For and about Montgomery Sailboats Subject: Re: M_Boats: Sheaves for masthead. The reason for wire halyards is reduced stretch. As the sail loads up the halyard will stretch resulting in the luff going loose (for hank-on headsails and mains with slugs scallops develop). Luff tension needs to be constantly adjusted - more as the wind speed increases and less as it goes lighter. (I'm sure JerryM and GaryO and maybe StanS can add even more details and point out where I have oversimplified things.) Having a wire halyard reduces the number of times needed to adjust tension. (The main's luff tension is more easily adjusted with a cunningham or, as the M17/15 have sliding goosenecks, with a downhaul line attached to the gooseneck's ring.) 'Way back when' line (aka rope) was way stretchy so wire was the best option to reduce stretch. My family's boat, built in 1979, when I was growing up had a 100% wire main halyard and a rope to wire jib halyard. There are now may excellent low stretch lines available meaning wire halyards are not necessary. Example: Dyneema. Some of these new lines are stronger than stainless wire (I use Dyneema for SWALLOW's lifelines and topping lift). The issue for some low stretch line is it is slippery to the hand and some even are prone to slip on cleats. Go to a chandlery and get a real hands on and purchase something you like when actually feeling it when gripped. For the M17/S17 the main halyard is 1/4". The jib halyard is 5/16". :: Dave Scobie :: M6'8" #650 :: SV SWALLOW - sv-swallow.com :: former owner M17 #375 SWEET PEA - m17-375.com :: former owner M15 #288 SCRED - www.freewebs.com/m15-named-scred/ On Mon, Jun 29, 2020, 1:26 PM Gary Froeschner <msogggf@gmail.com> wrote:
Thank Jerry & Dave everyone else for the feedback.
The existing sheaves are definitely plastic and they definitely have a narrowing, radiused shoulder in the groove that appears to be designed for a wire, not a rope. I now know that they are not original. The new plastic sheaves I was able to get are designed for rope. I assume no one has any of the original aluminum sheaves.
Can you educate me a little on the pros and cons of wire verse rope halyards. I will need to make a decision of one approach or another. Would like to make the right one.
I did find one source for brass sheaves that were fairly close to the right size. They are casting rough and require finishing which I can handle. But, I was concerned with the dissimilar metals issue. SS pin, aluminum masthead, & brass sheaves. Aluminum or plastic sheaves sound better to me.
Dave, to answer your questions, I will be rigging each time I sail. (if that ever happens) I live in Missouri and will be sailing in lakes using it primarly as a trailer-able daysailer with occasional overnights. Unless – I go to Florida to buddie sail with my brother in the bays around Destin this summer.
Thanks again.
Gary Froeschner
Sent from Mail for Windows 10
From: jerry montgomery Sent: Sunday, June 28, 2020 1:40 PM To: For and about Montgomery Sailboats Subject: Re: M_Boats: Sheaves for masthead.
All the xsheaves I put on the boats (both 15's and 17's) were of 3/8 aluminum. I'd buy a sheet, probably 4X4 cut it up into 2" squares with a combination of a table saw and a band saw, drill the 1/4" holes, then have a machinist turn them on a lathe with the outside diameter 1 1/2". I'd get several years' supply with a day's work and less than a buck apiece to the machinist.
If you can only find plastic ones, I use them and swatch to no-stretch rope halyards.
jerry
________________________________ From: montgomery_boats <montgomery_boats-bounces@mailman.xmission.com> on behalf of Dave Scobie <scoobscobie@gmail.com> Sent: Sunday, June 28, 2020 11:17 AM To: For and about Montgomery Sailboats < montgomery_boats@mailman.xmission.com> Subject: Re: M_Boats: Sheaves for masthead.
I find it unlike the original sheeves were plastic.
Are you rigging each time you sail or is the boat on a mooring? If rigging each time you can inspect the sheeves after each time going out and see how much wear you are experiencing. This is a solution of deferring maintenance until you get a set of rope halyards and also has the danger the wire halyard gets jammed when the sail(s) is raised.
:: Dave Scobie :: M6'8" #650 :: SV SWALLOW - sv-swallow.com :: former owner M17 #375 SWEET PEA - m17-375.com :: former owner M15 #288 SCRED - www.freewebs.com/m15-named-scred/< http://www.freewebs.com/m15-named-scred/>
On Sun, Jun 28, 2020, 11:03 AM Gary Froeschner <msogggf@gmail.com> wrote:
To continue my sheaves issue. Yes, my boat does have the wire halyards. The sheaves themselves are failing. They are plastic and have become brittle and starting to crack.
I did not anticipate replacing the wire with rope. In fact, I already replaced the old ropes and tied it to the wire just like the original set up. Obviously, the new ropes are too short to replace the wire too. Ugh.
I did get some new sheaves, but they are plastic and not exactly the same size as the old ones, but seem to work. BTW, they were the second set that I bought. The first set was all wrong, but that’s another story. In my research, it seems that plastic sheaves are not recommended for wire halyards, but that is what the originals were – I assume. Call me confused.
I assume that either I run with this new set up until it fails, or I replace the wire with rope which would be more compatible with the new sheaves. That will be the third set of halyards that I will buy and I haven’t been on the water yet. HA!
I would appreciate any advice. Thanks.