Substituting aluminium spars on the Oz Goose sail boat

by

The plans for the various Goose versions show timber spars, butwhat about Aluminium tubing for spars. Here are sizings in Imperial and Metric below.

Here is Brad Hickman practicing on Lake Eufala. Video below.

For information on Building and sailing an Oz Goose

I do like the timber spars because they look nice.  But you can save a bit of weight on the yard by using an alloy tube.

Brad Hickman did all the work on this and with a suitably modified boat derived from the OzRacer went on to win the PDRacer worlds.  Six months after (???) there was an anonymous challenge to the legality of his boat.  So it was measured and was found to be class legal. His boat is the one in the pic.

Correct Choice of Aluminium Alloy for Lug Masts and Spars

The correct aluminium alloys to choose for boat spars are in the 6000 series. The Temper must be T6 or the alloy will be too soft and the mast dent too easily or fold at the partner.

So typical numbers you will see are
6061-T6
6063-T6

A newer alternative below is a lower temper but has the same strength. The T5 Temper is not appropriate for the alloys above.
6005-T5

Aluminium spar diameters and wall thicknesses for the Oz Goose and OzRacer.

Also Ocean Explorer, Ooze Gooze and Goose Explorer

SparDiameter insDiameter mmWall thickness insWall thickness mm
Mast
Oz Goose
Ooze Gooze
Goose Explorer		2.56650.082.0
Mast
OzRacer RV or Mk2
Ocean Explorer		2.44620.082.0
Yard1.5370.0651.651
Boom2500.0651.651

Notes

1/ I do think the mast will look much less nice than the timber version which has a classic taper.
2/ We do have a nice timber box boom design now.  Contact me for details or see the “files” section on the Goose Facebook group.
3/ A class Legal Oz Goose can only use timber or untapered aluminium Yard. However the other boats have a Yard option of using a used 50% (or more) carbon spar from a windsurfer. Some regions they are very affordable. Here are the details and the instructions. NOTE – WINDSURF SPARS ARE NOT SUITABLE AS MASTS FOR THIS SIZE OF BOAT. THEY ARE FAR TOO FLEXIBLE AND THEY ARE TOO EXPENSIVE TO STIFFEN.
Using a windsurfer mast for a lug rig yard on a Goat Island Skiff – Storer Boat Plans in Wood and Plywood

Aluminium spars in use on an Oz Racer

And just for general fun, here is Brad using the spars to motor upwind in his OzRacer derived boat using the Aluminium spars.

More Information about the Oz Goose

For information on Building and sailing an Oz Goose

5 thoughts on “Substituting aluminium spars on the Oz Goose sail boat”

  1. I need to build a 3-part mast. Would 2 1/2 OD still be correct? I’m figuring my inner sleeves would be 2 feet each– 1 foot on each side of the split. Does that sound right? And is there any problem with using wooden yard and boom with an aluminum mast?

    Thank you.

    • Absolutely fine. One option is that the top third of the mast can be the same section as used for the sleeve. It will save a little bit if weight and the taper effect will help the appearance.

      MIK

  2. Thanks very much, Mike. Re-examining this (after looking at the vendor and shipping options), I’m thinking of a 4-section. Bottom 2 sections would be 2.5 OD, upper 2 sections would be 2.25 OD, and top 15″ would be 2″ OD. All wall thicknesses would be 1/8″, not the 1/16″ mentioned above. Sleeves would be inserted 9″ into the outer tubes. Total weight for the mast would be around 25 lbs. Does that sound reasonable to you?

    • Hi Chris,

      Normally a two piece aluminium mast will be lighter than the timber equivalent. . A three piece mast starts to be somewhat heavier than a timber mast and four piece heavier still.

      I don’t know why you are planning to double the wall thickness – it will be a tank. Is there a problem getting the approx 1/8″ wall in the table above?

      if there is no real compelling reason to go four piece I would go two or three.

      After all, the yard and boom are already longer than half the mast which defines the stowage length. Looks like overkill unless you have something really specific in mind.

      Saving weight in the rig is probably four times more effective than saving weight in the hull, but both will give you noticeable differences.

      MIK

  3. Thanks very much. The vendor says that the shipping has a surcharge for pieces over 58″. I’ve asked for more specifics about that surcharge, but I would guess I’ll end up with a 3-part. The vendor hasn’t responded with more specifics, yet.

    C

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.