Jet-14 Mast Set-up Guide

Editor's Note: Since I wrote this article in 2000, the DM-1 has truly
become the Class standard, and there are many people that have built
lots of rigs.  This is a good starting place if you are going to do so,
but don't forget to talk to the real experts, like Greg Koski, Brent
Barbehenn, Bob Putnam, Mike Parramore, and Dave Michos.  

Dirk.

Part I: Getting the Hardware

 

            Last year I had the opportunity to build two DM-1 masts from bare pole

to completion.  Its not too hard, but it does take some time.  This

series of articles will guide you through assembling the hardware,

putting it all together, and finally tuning it up.  The key with the

DM-1 is build it STRONG.  If you don’t, it will come down.  Minimize the

holes that you cut, and make sure that your pop rivets are stainless

steel and of sufficient diameter.  I failed to fully heed this warning

with my first mast, and I’ve never been able to match the speed I had

before it broke. 

 

Before you begin, I recommend that you make a diagram (or use one from

the class rules) that shows exactly what parts you intend to put where. 

This takes a little time in beginning, but will save time in the long

run.  The key question you will face is whether to run your halyards and

controls internally or externally.  I chose to go outside with

everything on my second mast because it takes a lot less time, its

easier to inspect the lines and you end up with far fewer holes in your

mast section.  Many people go internal because it reduces windage and

looks much better.  Most people do not put the spinnaker halyard

internal, however, as this requires a hole in the unsupported upper

section of the spar. 

 

            In order to begin, you will need:

 

     1. A copy of the class rules, with the mast diagram--it contains

all necessary measurements.  If you are confused, there is an article

discussing this topic in Jet Blasts before last years Nationals.

     2. A DM-1 mast section.  There is a $75 shipping fee so try to

order with a group to spread the cost, or go pick it up when you’re in

New England.  When I ordered, I ordered with a group through Mike

Parramore, as he gets a dealer discount.  You can check with Greg Koski

about this as well.

                Dwyer Aluminum Mast Co.

                2 Commerce Drive

                North Branford, CT 06471

                (o) 203-484-0419

                (f) 203-484-2014

                Website address: I don’t have it handy, but its on the web. 

 

     3. When you order, get the following parts from Dwyer

            a. Section: 22 feet (check this against your old mast) (about $175).

            b. Mast butt: Part # D 212 (about $7.00).

            c. Sail feed slot: cut it 56 inches from the end (check this against

                your old mast) (about $6).

            d. Hound fitting: (where the shrouds attach to the mast) I don’t have

                the part number, but specify that it fit the DM-1 section. (about $20).                       

 

     4. Spreader assembly (Including spreader bracket and airfoil

spreaders)

            a. I believe that Dwyer has a spreader bracket and airfoil spreaders

available for the DM-1.  This will be the easiest option by far.  Get a

bracket that fits the DM-1 and wraps around the front of the mast, as

opposed to one that comes in two different pieces.  Get airfoil

spreaders that fit the bracket.  Most top boats have spreaders between

17 and 18 inches (measured from the mast to the tip of the spreader). 

Order 20 inches and cut them accordingly--after you can measure with the

bracket. 

            b. I personally did not get Dwyer spreaders, as I wanted to have

spreaders where you can adjust the angle and the length.  (I couldn’t

find anyone that really knew what the angle or length should be, so I

didn’t want to assemble them permanently until I could test my own

settings).  Instead, I got Proctor pieces at Annapolis Performance

Sailing (800-729-9767) and customized them to fit the Dwyer section. 

                1. Proctor extendible, adjustable spreaders (Part # PR009) (about

                    $75 per pair).

                2. Spreader lug for adjustable spreader (Part # PR 020)

                    (about $22 per pair).

                3. Front wrap spreader bracket (Part # PR019) (about $20)

 

     5. Main halyard assembly

                        a. Dwyer offers a main-halyard block for the DM-1 (Part # D 101)

(about $14).  I personally felt that it was too high profile, and I

didn’t like the idea of nylon sheaves.  Without question, however, this

will be your easiest and cheapest alternative. 

                        b. I chose to go with two through-blocks, one through the front of the

section, and one through the wall underneath the sail track.  As

discussed below, this requires much more work, including hack-sawing off

several inches of sail track.  If you go with this option, get the

smallest available through blocks.  If you anticipate using wire for

your main halyard (I used Vectrus 12 (Vectran) line), make sure you find

blocks which are designed to handle it.

                        c. If you choose to run your main halyard internally, you can just go

with one through block at the top, and cut a hole down low.

           

     6. Miscellaneous:

                        A quick list to consider, some of these things you can probably strip

from your old stick, otherwise, talk to APS or some other knowledgeable

hardware outlet. 

                        a. Halyard lock: I put mine at the top of the mast to decrease

bowing--its a hassle to get the sail down though. 

                        b. Spinnaker halyard block and fitting: you want a flat thing with a

loop on it to hang the block from.

                        c. Jib halyard fittings: through block if you’re going internal.  If

not, block and shackle to hang from the hound fitting.  Consider how you

intend to cleat or control the halyard to determine your other fittings. 

(I have mine to a magic box so I can control tension).

                        d. Topping lift block and fitting.

                        e. Chafe collars: I mounted my spreaders over a Proctor (blue) chafe

collar (Part # PR 032, about $20).  You have to custom bend them to fit

properly.  I recommend putting a chafe collar at the spreaders, the deck

and the butt if you have internal controls exiting there.  Dwyer also

sells a what it calls a mast splice that serves the same purpose.  As I

understand it, they go internally, but I’ve never used them. 

                        f. Boom vang bail or tang: there are a variety of options here.  I

used a basic bail and bent it to fit around the chafe collar. 

                        g. Mast butt block: If you go internal on your halyards and controls

you may want to consider a multi through block for the base of the mast. 

You may also want to consider halyard exit plates instead. 

                        h. Stays: I don’t know how anyone figures out how long they should be

before they put the mast up, but good luck.  The Dwyer hound fitting

requires a thimble-eye for the upper end of the stay-- you can use your

old fittings at the deck. 

 

Part II: Finishing the Mast

 

            As I mentioned before, the chief concern here should be that you build

a strong mast.  The basic tools that you will need are a tape measure,

magic marker, power drill, set of metal files, hacksaw and a top quality

pop-rivet gun that can pull stainless steel rivets.  Before you begin,

you will also need to borrow or make a c-shaped thing to measure the

distance from the bottom of the keel to the black band above the deck. 

Again, this is beyond the scope of this article, but look at Ralph

Hanson’s article from last summer.  Your local measurer should have one.

 

            The most time consuming part of building the mast is cutting the holes

for through-fittings.  I approached it by marking the outline of the

fitting with a pen, then perforating inside that mark with the drill. 

Once perforated, I broke the piece out, then filed the hole to size

using an appropriate size file.  This will go fastest if you have a few

small files and some larger ones.  I have heard of people using a router

to cut the holes, but I never tried it. 

 

            Step 1: Measurement:  Place the plug in the bottom of the mast, put the

mast up and make your initial band above the deck.  Check this about

twenty times, because if its wrong, you’ll have to do everything over. 

Use that to measure and place the other bands.  Then mark the spot where

you will put the spreaders, jib halyard block, topping lift, etc.  I

riveted the plug on later so I could get all of the aluminum shavings

out.  I also drilled holes in the bottom so that the mast will drain. 

 

            Step 2: Main halyard: If you use the Dwyer fitting, just pop it on,

drill some holes and pull the rivets.  If you use a through-block, you

will need to use a hacksaw to saw off about the first five inches of

mainsail track, before starting the hole for the fitting.  I put my

halyard lock about six inches below the top of the mast.  This reduces

the tension on the spar when its breezy, but it makes it more difficult

to get the sail down, particularly when you’re away from the dock. 

 

            Step 3: Spinnaker Halyard:  Pretty self explanatory.  I used a rotating

block. 

 

            Step 4: Hound fitting: I strongly recommend the Dwyer hound-fitting. 

The most difficult thing about it is that you have to drill a large hole

through the center of the section.  I found it difficult to get the hole

level.  After screwing it up, I used a round file to file one side lower

so that the two sides were approximately even. 

 

            Step 5: Jib Halyard: On my second mast, I simply hung the external

block from the hound fitting, so that the halyard and forestay attach at

approximately the same point.  On my first mast I went internal.  If you

do the same, be sure that the block be as near the hound-line as

reasonably possible. 

 

            Step 6: Spreaders: This is the most complicated part, and the part that

failed on my first mast.  I think that my problem was that the rivets

that I used had a head that was too small.  The spreader bracket pulled

over the top of them (we were going downwind with the kite up), and the

spreaders blew forward.  The second time, I took a blue proctor chafe

collar, and bent it down so that it takes a lot of force to snap it over

the section (I beat it with a hammer, the darn things are pretty stiff). 

I mounted the spreader bracket over the chafe collar, then riveted the

spreaders onto the whole thing.  If you are using fixed spreaders, it is

my understanding that you can drill multiple holes in the spreaders, so

that you can drop the pin in at different places.  If you are using

adjustable spreaders, you will also have to drill and place the lugs. 

There’s not too much room to do this so plan carefully.  Most boats have

their spreaders between 17.5 and 18 inches measured from spar to tip.  I

think mine are 17 7/8 inches.  I had to use the hacksaw to get them the

right length. 

 

            Step 7: Deck: put a mast chafe collar where the spar goes through the

deck.  Put a vang tang or bail as low as you can, and make sure the bail

is bent down so that it doesn’t hook your sheets. 

 

            Step 8: Halyard Exits: If you use internal halyards, figure out how to

get them back out as is appropriate for the set-up of your boat. 

 

            Step 9: Rig it: halyards, stays etc. 

 

            Step 10: Make sure that there is nothing sharp anywhere on the spar. If

so, file it down or wrap it with rigging tape. 

 

            Step 11: Rig the boat in your yard and figure out what doesn’t work. 

Fix it. 

 

Part III: Tuning the Mast:

 

            Once you have completed the mast, you probably want to know how to get

it tuned up nicely.  I definitely don’t have the final answers on this

issue, but you can bring my article to real class studs like Koski,

Barbrehen, Simonds or Bill Buckles, and they can tell you what I do

wrong.  I do suggest that you keep a log of the settings that you use

each day of racing, so that you can test and recreate settings over

time.  This is only way to know whether that 1/4 inch change in rake is

going to drive you to victory or spit you out the back. 

 

            Step 1: Set the butt.  Long-time Jet wisdom says that the butt of the

mast should be 19 inches in front of the centerboard pin.  Recently,

there has been some movement to try setting it further forward, as Brent

Barbrehen does.  If its between 19 and 19 5/8, you're probably fine. 

 

            Step 2: Set it at the deck:  Be sure that the hole in your deck is in

the middle of the boat, and directly above the mast step.  If you are

going down from a DM-2 or a wood mast, you will probably need to build

up the sides of the hole anyway, so get it straight. 

 

            Step 3: Make sure its in column: Tighten the shrouds a little bit and

run tape measure up your main halyard. 

First, sight up the sail track and make sure that the mast isn’t bowing

to either side.  If it is, it may be a problem at the deck, with the

length of the spreaders or angle of the spreaders, or with the relative

length of the shrouds.  If it looks like the problem is at the

spreaders, make sure your spreaders are the same length and that they

are coming off the spar at the same angle.  Take the mast down and stare

at it for twenty or thirty minutes if you can’t decide.  (Well, that’s

what I do, anyway).  If it appears that the problem is at the hounds, be

sure that you have the shrouds the same length, and that you hounds pin

is level in the mast. 

Second, measure the distance between the tip of the mast and deck just

aft of the shroud attachment.  If this measurement is not within a

quarter of an inch, adjust the stays, if possible.  In any event, get it

as close as possible to even. 

 

      Step 4: Set the rake and tension: 

The object here is to get the rake right, while getting the shrouds at

the right tension.  Since most people tension using the forestay or jib

halyard (which pulls the mast forward and decreases rake), this is a bit

of a balancing act.  I measure the rake from the tip of the mast to the

top center of my transom.  If you have a glass boat, your transom may be

lower, so adjust the numbers accordingly.  Most competitive Jets sail

with their rake between 20 feet 9 inches and 20 feet 10 inches.  I set

my boat up so that it is at 20 feet 8 3/4s with minimum tension (about

75 pounds).  I then tension my jib while under sail, which presumably

pulls the mast tip forward.  Most people sail with tension of between

100 and 200 pounds on the side stays.  I haven’t found any speed benefit

from more tension, but you might try it in a blow. 

 

      Step 5: Set the bend:

This step is pretty optional.  When you pull on jib halyard and

mainsheet tension, the spar bends in funky ways.  It is difficult to

predict these changes without looking at them.  If you have time (which

I never seem to), strap your boat to the trailer and run the sails up. 

Tension the jib and main and look at the mast.  I try and set up the

boat so that there is nice even curve through the entire spar.  This

means restricting the forward bend at the deck somewhat--I have a mast

ram for this.  T-blocks that drop into the slot, or a line that runs

around the front of the mast will also work.  If you have adjustable

spreaders, you can restrict bend by moving the spreaders tips forward,

encourage it by moving them back.  Don’t go too far either way, however,

as this creates high loads. 

 

      Step 6: Go sailing and whip some butt. 

 

                                               

                                                                        Dirk Schwenk