Broken Main Mast 105'- need help

I am not a wooden sailboat experienced Naval Architect generally I play with large steel boats. However I have been tasked with helping to find a temporary repair and ultimately rplacement for a broken main mast on a 85 year old 102' Marconi rigged ketch. The main mast broke approximately 2' below the mast head fitting.

This vessel is sailed hard and is rigged with a large spinnaker which would not have been original to the boat. I assume this to impose almost horizontal loads at the mast head? Also the stays from the spread don't tie into the mast head fitting like I thought they would they attach to the main mast down about 3' by saddle fittings? It is just above these that the mast broke. should the stays tie into the mast head fitting so less moment is put into the mast and it is more of a pin connection at the mast head for the mast(pillar)?

I have attached a few photos as you can see there is a lot of bolts and even a wood insert? No doubt these weakened the mast. Can a steel pipe be put over the top of the existing mast and the tied into the masthead for a temporary fix until a new mast can be sourced?

Any advice is welcomed or if you know the name of an expert in British Columbia that would be great.

 

Maritimer,

Steel pipe would not be a great idea, it would add new point loads to the joint area. Best temp fix will be new wood scarfed on to the existing stump. This can last a long time and if done properly be as strong as the old mast. Sitka Spruce or Douglas Fir would be first choice of material.

Drop me a note direct for more info.

Tad

 

I assume that the fingers, shown in the first picture, are attached to a live person. Said person is gutsy as hell to have gone 100 feet high on a questionable mast.

 

Have seen a gaff (~200kg) that broke and a quick repair was needed, a steel sleeve was fitted, as far as I know it is still in use now some 10years after being fitted.

I would agree that a better fix for your mast would be to scarf new wood on and provided that it is done correctly you will not need to replace the mast.

 

A scarf is the only good long-term solution. The longer the better, maybe 12:1 or 15:1. The wood used to repair would therefore be at least 12 times as long as the mast is thick, plus the length above it. The wood should match the original in species, grain width, and grain orientation. Epoxy adhesive is the most reliable glue.
The rigging in the photo is the absolute best type for strength, looping around the mast as it does. It's superior to any other means of staying.
The failure may have been due to any of the following: Stay terminal failure, shroud terminal failure, excessive cracking from shrinkage over time, rot, positioning of spinakker attachment point not being properly engineered, weakening holes drilled, or twisting from rotation of the spinakker stressing at the attachment point. The pivoting headsail is best carried by designing the axis point to be the same as the mast centerline to avoid twist. If located on the forward face of the mast, a sudden puff can put an enormous twisting load on the masthead. A pivot on a cap atop the mast is a good way to avoid the problem next time. If the attachment point is lower, a wire bridle around the mast will do the same and better if well designed.

Alan

 

spinaker connection

I think your point on the spinaker connection point is a good one. In the photos it appears that a peice may have been added to allow the spinaker to attach which is far from the mast. The moment would be considerablly larger than if attached at the mast. I will pass that along to the vessel.