How do I attach the forestay to this bowsprit?

[Rivers & creeks]

I need to move the forestay back about 12 inches so that it doesn't fly the chute or the new hanked on genoa. My thought was a U bolt through the two layered bowsprit which is iroko and stainless, with a top and backing pad added. One chap I asked was dubious, he said it would need its own dolphin striker to match the one on the end of the bowsprit? What's your thoughts? By the way, no need to shorten or lengthen the forestay, as it comes back the fitting is lower and the two changes cancel each other out.

The suggested U bolt would go at about the end of the anchor shank where it joins the chain and a few inches to the left in the mid line.

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[Bilgediver]

Do what you suggest and your genoa would be flying on a wing and a prayer. There is no obvious strong attachment between the inner end of the bowsprit and the deck of the boat. Even if there was you would need to know how the load path would be dealt with at deck level. You need to confirm in your own mind at least how the deck and its attachment to the hull are engineered around the bow area. In the current set up these loads are dealt with by the Dolphin striker and there is little or NO load at the inner end of the bowsprit.

A U bolt just through the bowsprite at this point might be a disaster waiting to happen. The load would have to be carried to the deck below somehow and it might not take it in this area without mods.

 

[Rivers & creeks]

Yikes! What about an additional cable from the underside of the U bolt to the point when the other dolphin striker is attached to the hull?

 

[William_H]

The loads on the bowsprit will depend on the distance the new forestay is attached aft of the existing dolphin striker as related to the distance the new forestay is from the attachment at the base of the bowsprit. Simplistically if the new forestay was attached half way between the dolphin striker stay and the base of the bow sprit then half the forestay load will be on the dolphin striker and half on the base of the bowsprit trying to pull it out of the deck.
The other concern in this scenario is that the bowsprit itself will be trying to bend/ break in half. It's stiffness and strength needs to be considered.
The bow sprit will have been primarily designed for taking end on loads produced by the old forestay and the dolphin striker.
The person who said fit another dolphin striker stay is right in that this would be a conservative approach to the problem. I think I would fit one. However the closer the new forestay is to the old position then the less need for a new dolphin striker stay. So if you attach the new forestay at a point 3/4 of the way, base of bow sprit to end (old forestay) then 3/4 of the load will be taken by the existing dolphin striker and only 1/4 of the load on the base of the bowsprit. the bending load on the bow sprit will be far less. Any further forward for the new forestay will be even better.
So I can not say if you need a new dolphin striker. Certainly it would be safer but only complex engineering analysis would determine if it is necessary.
A U bolt or saddle with backing plate providing they are big enough should be fine in both cases. A saddle underneath could form the attachment for a new dolphin striker stay. Down to the original bow attachment should be fine. Just remember the loads on a froestay can be huge with a big jib full of strong wind. good luck olewill

 

[Rivers & creeks]

Thank you for such a detailed reply, it's very helpful. When the bowsprit was added about ten years ago - before my ownership - the yard said that because of the design of the sprit, the dolphin striker was uncessary but the owner insisted. I'm inclined to agree with the previous owner. The alternative is to fit a proder for the chute and leave the Genoa where it is but off the shelf proders are £1,000 which seems insane. I've wondered about getting a two foot length of scaffolding pipe and having it chromed to look good. One foot protruding, the other foot fastenened to the existing sprit. In that scenario all the loads are on the end as at present. What do you think?

 

[William_H]

Having an existing dolphin striker down stay for the bow sprit means that it would be easy to fit another for a prodder extending the bow sprit further forward. Spectra or dyneema can be used as the actual stay using the existing bow fitting.
If the prodder was to be used without a stay down wards to the bow it would need to be large enough to be stiff over the unsupported length and attached near level with the bow giving support ina down ward direction. The inner end would tend to press down wards into the deck so not so much worry. However do support the prodder sideways as well as a code 0 or whatever you call your assymetric spin will pull sideways a lot.
So use of the existing bow sprit with spin on the tip would look a lot neater it is just a question of whether you can have the main inner forestay further in board. It will mean more fouling of the jib on the mast or baby stay when you tack it will also mean the ideal sheeting point will move aft . It also may mean the jib leach might foul the side stays. So check all this out before you move the main forestay. good luck olewill