New mast in old boat and what to do about the partners

[allene]

On the Garhauer approach, what if I hold it down with a 1/4 inch bolt every 1.5 inches. That would be 26 bolts and 6.5 inches of linear surface compared to 8 inches for the mast partners. If that wasn't enough, I could use 5/16 bolts and get 8 inches. Seems like bigger bolts would do the same thing as spacers although it would be threads in one case and a smooth surface in the other unless the bolts had a significant unthreaded section like a carriage bolt.

[Brion Toss]

Hi again,
That kind of spacing would be a net loss; too much material removed. Wood is strongest in compression, and that is what the bolts will be applying, as the mast tries to move them sideways. Bushings are your friend here, providing surface area.
Another way to look at it is that the mast doesn't need all that partner surface area; there is just no way to have any less. I think that as few as 6 bolts, properly bushed, would be fine.
Fair leads,
Brion Toss

[allene]

What size, kind of bushing? Not fully understanding yet. I need way more than 6 bolts to hold the plate down so are you suggesting bushings on only some?

Allen

[Brion Toss]

Hi again,
The primary load on those bolts will be in shear. Even if the deck plate doubles to support halyard turning blocks, it is most unlikely that any halyard would provide even a 1,500lb vertical pull; tensile strength of a 5/16" bolt is about 8,000lbs.
1/4" wall bushings would be fine, and on all the fasteners. Thicker is better.
Fair leads,
Brion Toss