question about tapering aluminum mast and forestay placement

[Southbound]

Greetings and thanks in advance for any assistance and opinons you may offer.

I am in the process of doing a DIY mast replacment and will with the help of very competent welders and engineers will be tapering a 56' mast section and chaning the mast head set up to be fractionally rigged.

When placing the weld in 7/8 rig attachment on the mast, what are the thoughts in placing it at or just above where the bottom of the taper starts? The original plan was to place it beneath the bottom of the taper like most masts I have seen. However that allows for only about a 3'6" taper.

Thanks,

[Brian Duff]

You should call Greg Tetrick, he is a great resource for that kind of info.

i think the taper can start wherever you want it to to get the right bend , providing the compression can still be managed.

[Southbound]

Thanks Brian.

I am not sure who Greg is but I welcome any insight he might offer. If he is willing to share his thoughts, Who is he and where might I find him?

I would like to take the taper down maybe 4 or 5 feet on the mast that is about 50 feet above the deck. It is a beefy section so I think we should be OK to put the stay fitting attachment about 1 foot above where the taper starts. We will have a fully penetrated strong weld. I know that in professionally built tapered spars the shrouds are often attached to the tapered area when a mast head rig.

Regards,
Jeff

[Douglas]

Hi Jeff , does your welder have a way to reduce the rippling of the mast wall all along the welded area ?

If so ,,,, please share that info with us .

Douglas

[Southbound]

Originally Posted by Douglas

Hi Jeff , does your welder have a way to reduce the rippling of the mast wall all along the welded area ?

If so ,,,, please share that info with us .

Douglas

-Well we will see fairly soon. This will be the first time that he has done this however he has succesfully welded up aluminum engine blocks that have had con-rods thrown through them so he has some skills!

[Douglas]

Hi Southbound, BTW , I have seen a heap of weld spater and globules on the back side of a plate/flat joint TIG welds, as well as the rippling along the joint, especially on aluminum.

This happens with similar flat plate joint welding on stainless steel, but I have been told that this back side spatter can be reduced if the Argon gas is flooded around the back side weld area as well as the outside weld in progress.

Argon gas is not expensive and it is heavier than air .

Let us know if this is useful info .

Douglas

[Brian Duff]

Mike,
Pete knows about argon flooding. Most of his work is done that way, i.e. in a box on the bench to keep the gas around the back side, or filling voids with gas to protect the weld zone - as you know, Pete is a bit anal about all that. he is one of the few welders you see working on boats that INSISTS on tenting off any outdoor areas that welding must be done in, to protect the gas sheild from distruption.

The way to prevent rippled mast walls is with a PERFECT fitting seam, no un-evenness can be tolorated. A lot of folks think the joint just has to be close, and the weld will fill the rest - it doesn't work that way. I think its somethign like the weld zone shrinks and then uneven fit causes ripples. Also, the area should be tacked and tacked and tacked to stablize before fully welding. Securing the back of the mast to an I beam with some blocking to pre -curve will also result in a better job, to keep the back of the mast straight.

Splatter and all inside may also be a result of incorrect temperature? Pete will know better.

Greg is the tall skinny guy with dark hair that works for McAteer, used to work with me, and at Tartan - super smart rigger and he will share, tell him HI from me and Jay Gallager too...