Yellow Ballad
Well-known member
I've designed a chainplate on SketchUp (to learn a bit about 3d design programs during lockdown) and posted them on the Jester Facebook group, two people who's opinions I respect have mentioned about bolt spacing being too close.
In the interests of learning more, I thought I would open this up to the forum for discussion and hopefully pointed to information on what's best.
It's 500x75x10mm the three centre bolts are 125mm c2c away from eachother, the doubled up ones 37.5mm c2c and in the middle distance of the three central ones. My thought the offset ones would spread the load onto more area od the grp. The plan was to affix with thickened epoxy oversized 10mm G10 to the inside of the hull (approx 12mm thick) and glass over it, then use 3mm s/s backing pads, I could also attach the actual plate to the outside of the hull using a permanant type sealant as belt and braces. Obviously this is all man maths which was the principal of it it looks like it's strong... but obviously only a fool would ignore warnings.
Now Jim Jordan's straps are thinner, narrower and shorter but recommends nearly as many bolts.
Are any of you guys smart enough to calculate the loads, stresses etc or offer advice either way/post grp being damaged by being ripped out or cracking from bolts being too close together.
Many Thanks.
In the interests of learning more, I thought I would open this up to the forum for discussion and hopefully pointed to information on what's best.
It's 500x75x10mm the three centre bolts are 125mm c2c away from eachother, the doubled up ones 37.5mm c2c and in the middle distance of the three central ones. My thought the offset ones would spread the load onto more area od the grp. The plan was to affix with thickened epoxy oversized 10mm G10 to the inside of the hull (approx 12mm thick) and glass over it, then use 3mm s/s backing pads, I could also attach the actual plate to the outside of the hull using a permanant type sealant as belt and braces. Obviously this is all man maths which was the principal of it it looks like it's strong... but obviously only a fool would ignore warnings.
By Jim Jordan:
The optimum attachment for the drogue is clearly a strap similar to a chain plate, bolted to the hull at the corners of the transom
This arrangement feeds the load directly into the hull and imposes no bending or pullout loads on the hull or deck. For a load of 14,000 lb. a strap 1/4" x 2-1/4" x 18" attached by 6 - 3/8" bolts.......
Now Jim Jordan's straps are thinner, narrower and shorter but recommends nearly as many bolts.
Are any of you guys smart enough to calculate the loads, stresses etc or offer advice either way/post grp being damaged by being ripped out or cracking from bolts being too close together.
Many Thanks.