Replacing mast step in a Prout 35

[StefanSG]

In structural engineering terms this is a compound lattice structure. The whole skin is monococque reinforced by bulkheads and internal structure which even includes furniture etc. The mast applies a point load which is considerably higher than that applied by a monohulls mast by virtue of the fact that the vessel does not heel. The mast loading is spread to a certain degree by the plate it is mounted on but this plate and the bulkhead it is adjacent to are insufficient in themselves to take the load without additional reinforcement. Hence the mast post which on early models was not sufficient in itself because the mast is forward of the post. One could argue that the answer would be to move the post forward but then it would not give any additional strength to resist compression of that bulkhead. The compromise developed on later models was to bond the post to the bulkhead and reinforce it at floor level with a transverse beam. Then a gallows strut was added to reinforce the mast mounting plate forward to stop the stress cracking which was often found on early models around the extremities of the mounting plate. I hope this answers the OP in detail and removes any confusion regarding subsequent posts.

Thankyou, it does. I’ve seen a few of these Snowgeese “remodelled” - taking out the kitchen units, berths etc.. quite worrying !

 

[boatmike]

Hi Stefan, glad to help. Have sent PM