National 125 Sailing Association

125 Discussion Forum

Please note: This forum is read by a wide group of 125 sailors.
This is not the place for personal attacks or inappropriate comments on anyones race, sex, age or sailing abilities.

Return to the Forum List

Building mast from tube section
Hi 125ers,
I am building a replacement mast for one that broke. The old mast was probably 25-30 years old ( No 386 ). I could install the old fittings on the new section using the building guide for the distances but I thought I should check here first about the current practices.

1/ Old mast seems to have had some sort of expanded polystyrene foam inside - is this a good idea/desirable?
2/ Building guide mentions using a compression tube at the jib hounds. What would I use for this and how is it installed?
3/ Old mast had a wire halyard and a fitting that acted as a halyard lock. It seems that current practice is to do without this and use a spectra halyard and some sort of cleat. Is this a better way to go? What type of cleat and where installed?
4/ I have seen on a few pacer masts a small hole in the side of the track to lead the halyard outside the track just above the cutout for feeding the sail in. This seems to be a good way to get the halyard out and in line with a cleat on the mast. Good idea or not?
5/ How to make the cutout for feeding the sail in and mounting the gooseneck?
6/ Old mast has the gooseneck on a short length of adjustable track. Is this still done or is a fixed gooseneck used and a cunningham used to adjust sail leech tension.
7/ While I am at it I would like to install the fittings for a spinnaker. Does the block on the mast hang from a hounds fitting or is it led inside the mast? If external how is the halyard turned and routed to the cockpit.?
8/ Same for the topping lift.

Thanks for any answers,
Regards, Davo ( Melbourne)

Davo29-Apr-2013    Edit    Delete 
Re: Building mast from tube section
Hi Davo
Dont bother with the expanding foam, just ensure the mast is sealed and has a drain hole near base.
Dont worry about a compression tube...not needed. You may want to consider a stiffener if your going to race though.
Lots of ways to do the halyard, depends if you want to be able to raise the main without tipping boat over while rigging. Modern line materials can replace wire. Best is to copy another boats method at your local club.
Grinder or nibbler to make hole in sail track but make it as small as possible to do the job or you will lose mast stiffness.
Dont bother with a gooseneck on a track....old technology/theory that didnt work and compromised the gooseneck strength. Use a fixed one.
All halyards and lines must be external to the fully enclosed section of the mast. This is mandated in the rules of measurement and construction.
The spin halyard and topper simply drop down the mast then can be turned around blocks or fairleads to somewhere aft along the centrecase. Some boats have tubes to lead the lines through the deck/bulkhead aft. Again, check out some boats locally.
Perhaps someone at the Vic association can assist?

Andrew3-May-2013    Edit    Delete 
Re: Building mast from tube section
1. The hounds through bolt is highly loaded and the hole through the mast wall will elongate and let water in during a capsise. Get some aluminium tube 3mm longer than the mast width, 1/4" inside clearance to suit the bolt. Mark out the position from the hounds fitting ensuring square in both planes, (up & around). Drll the hole for the tube outside diameter and lightly countersink. Countersink the inside of the tube end and place into the mast. With a ball pene hammer, pene the tube in an outwards direction to seal the joint. This will give the hounds bolt something to tighten up on rather than squashing the mast.

2. The gooseneck fitting takes all the thrust from the boom vang and the older track style were constantly having to have the rivets replaced. The load on the mast here dictates it must not be weaked by a cutout. I open up the sail track by straightening the curved part of the sail track wall. Place a flat screw driver or flat steel into the track and tap on the outside of the curve with a flat hammer. The track will open up. Tidy up the ends with a ball pene hammer and you with have a shape the sail will flow over guite easily rather than the sharp ends of a cutout. Make it roughly 70mm long from the top of the band style goosneck fitting.

3. Kevlar is OK for a mainsail halyard, however if you use a halyard lock near the head of the mast (my recommendation) the knot in the kevlar may be too bulky for the pulley on the top of the mast. A small swage in wire is thinner. Fasting the mainhalyard near the top is best to minimise halyard stretch and also droop when mast bends. I also like to rig with the boat right way up on the trailer/jinker. Too much hassle tipping it on its side.
Don Barnett3-May-2013    Edit    Delete 
Re: Building mast from tube section
Thanks for the responses.

I have ditched the old gooseneck and have a fixed one to replace it.
Tried to open up the track on the old mast for a practice but it has not worked very well. Tried using a screwdriver inside and a wooden wedge, but will keep trying, have a few metres of practice tube to go!

Don, can you describe your halyard lock?
This mast had it at gooseneck level and a long wire halyard but the other 125 I have looked at has a bail at the masthead and a fitting with a hook & bungy permanently attached to the head of the sail.

Speaking of the masthead, It looks like I cannot get the old one off, is the cast Al part used nowdays or is the mast just sealed and a block mounted above the black band ( like the sabres do ).

Thanks again,
Davo8-May-2013    Edit    Delete 
Re: Building mast from tube section
Davo, the halyard lock is a Ronstan RF191 mounted on the port side of the sail track section of the mast just below the black band. You haul the mainsail up by the halyard which has a small ball swage on it in the correct position. The swage passes over a pulley RF453 and is made captive in the halyard lock. There is minimal length of wire/kevlar to stretch. To fit the swage through the guard over the sheeve in the pulley open it up as required with a phillips head screw driver or punch. Don't use the 2 hole RF568/919 style as they will droop down the mast under load. The guide over the aft part of the pulley is important.

The sail track opening is best explained as, you support the sail track edge and straighten the curved side of the track extrusion back to the full mast section, by tapping inwards with a flat hammer. As the curve is straightened the track will open up. The reverse is applied to make neat ends. Support the opened up sail track and bend the aft edge of the sail track inwards with a ball pene hammer.
Although the attached picture does not show it very clearly enlarging it can show you the end result.

The old cast aluminium mast cap with sheeve. It may be held in with a screw or rivet sideways through the mast section. However this is obvious and I will not insult your intelligence. It is also possibly frozen in with corrosion. As the old mast is NBG cut through the old mast 25mm from the end then cut off the old section of mast by a series of holes and cold chisel.
Alternatively, a few hard taps with a hammer may break the corrosion bond and enable a screw driver to push the cast edge of the fitting out of the mast section with a hammer as a persuader. If in reasonable condition and the sheeve rotates freely this fitting would live again, unless you want to race seriously. If you can win races at the top level in boat no. 386 you would seriously embarass a lot of other 125er's.
Don Barnett10-May-2013    Edit    Delete 
Re: Building mast from tube section
Thanks Don,

I take it then that your halyard is reved closest to the mast then through the block, the lock and down the outside of the mast ( not down the inside of the sail track).

I'll keep hacking at the old mast and see how I go.

Hmm, yes, Given that "Dalek" has eaten an additional 1 1/2 sheets of ply ( new floors, cb case and foredeck ) a few litres of epoxy and 4 litres of paint/filler, even if I was capable of sailing at the front of the fleet it's a pretty heavy (robust? ) boat now.
Davo12-May-2013    Edit    Delete 
Re: Building mast from tube section
The tail of the halyard lies down the outside aft edge of the mast on the port side. I attach near the base with a short length of thin elastic shock cord via a couple of mini flag clips RF536. This lets you store the rope tail inside the mainbulkhead hatch and the halyard is kept tidy. Being a straight line from the masthead it is also an excellent guide to mast bend.
With this system you can lower/raise your mainsail on the water. Never know, you may want to go fishing!
Don Barnett12-May-2013    Edit    Delete 

Return to the Forum List       Add a message to this discussion
Measurer's Forum
Committee's Forum

  National 125 Association admin