Mastlength and masthead for spinnaker

[Pius Bielowski]

Hiya!

We hope to have our TIKI 21 in the water soon.

One of the last steeps is the constrution of the mast. We have ordered an aluminum tube but it is only available in 6 meters. So we will have to make wooden inserts on both ends. Are there any hints on how to fixate the inserts?

Concerning the mast we will follow the plan but I am thinking about two modifications:

Increasing the mastlength to 7m. I know about the importance of keeping the center of effort as low as possible but I imagine it would improve comfort on the plattform to hoist the main 50cm higher in light winds. Are there any experiences with this idea? We will anyway use 6mm wire for shrouds and forestay, the sails remain unchanged.

Secoundly I would like to use a spinnaker or gennaker. This means there must be a second halyard which exits the mast above the forestay. I have seen mastheads with a mastcrane and a pulley ahead similar to the arrangement astern for the gaff. Unfortunately this means the halyard goes down ahead of the mast and cannot be hidden by the luffpocket. I dont like the idea. So I am thinking about copying the jibhalyard disk-arrangment.

Please tell my your thoughts about this. Approved solutions and pictures are welcome.

Ciao

Pius

[Ian Bamsey]

I built my mast using a 6m alloy tube and wooden end pieces as suggested. If you follow this design, you can use heat gun glue to stick in the wooden ends. If they are not too tight a fit, glue them in and if you need to remove them a hot air gun will do the trick.

Ian

[Johan van Zwienen]

I finaly found an aluminum tube of 100 mm wall thickness 3 mm I'm thinking of adding about 50 cm. to get to a length of 650 Cm. Question : should I put longer stays or can I just put longer good quality cords to attach to the boat?

[Ian Bamsey]

If you have found a 6m tube, you can make up the 50cm with wood/ply epoxy fabricated inserts for the foot and crane sections. This might be easier than adding more aluminium.

[Pius Bielowski]

Concerning the shrouds and forestay I can say the folowing: our mast is 7 m long and I did a lot of calculation to get the right length of the wires. Somehow I got it wrong and the shrouds were too long. So we shortened them. Now our lashings are rather long but this is no problem. The next time I would step the mast with any makeshift rope instead of the stays and measure them. And I would go for dyneema lines in place of stainless steel. 

[Johan van Zwienen]

Done.

[agur paesüld]

Pius, I like your solution, as I have intention to go for gennaker as well for my Itatae. But tell me, did you epoxy coated the wood as well, before inserting it into the tube? If not, did you noticed any expansion/contraction of the wood due moisture?

[Pius Bielowski]

Yes, we did coat the inserts with epoxy. In the first three season the fit of the inserts was very tight. As I said before we hardly got it plugged together. Therefore we did not glue or screw them in the tube. This spring we noticed that we can rotate them a little bit. So they obviously contracted. I think it is no big issue since the whole mast is compressed by the stay and shrouds.

By the way the next time I would put some fiberglass on the semicircles were jib and gennaker halyard run. With time they cut grooves in the wood and the halyard can get caught in there. 

Fair winds

Pius

[agur paesüld]

Thanks for the remark.

... i think I will try to find a hefty sheaves with case to install instead of semicircles to avoid scuff.

[Éric Bouvéron]

Bonjour,
When you add a second halyard for a spi or gennaker, you have to put your rigging cleats between the two semicircles, or the forestay will be misplaced, since it is the lower semicircle which received the jib halyard?

[George Woodward]

Hi Kim

I am just  making an al. mast  for my 21 and i am planning to follow your advice on a sleeve joint and masthead crane. And many thanks for the information.

The sleeve drawing shows staggered  small holes . What is their purpose? Express adhesive  perhaps?  And how did you close off the top of the mast? (I have a 21 in Turkey but can't remember/ don't have a photo to help

Regards George

Johan van Zwienen said:

Hi Kim, thnx for the reply, clear, nice pics , good explanation.way?

kim whitmyre said:

Johan, no such tapering is necessary (or possible!) for the inner pipe/sleeve. Here is a picture that will clarify:

You cut a slot in the sleeve that is wide enough to allow its compression to fit into the inner diameter of the mast. In the picture above, I was doing a test fitting of the sleeve into the mast pipe. The large "hose" clamps were more than strong enough to compress the sleeve.

Rivets or screws are used to fix the sleeve, yes.