replacing/enlarging masts on a wooden fishing boat

This is a conversion of a wooden fishing vessel. The boat is from Scotland, built 1958. It is listed as a national historic ship in the UK. Here is the link: Name Comrades | National Historic Ships https://www.nationalhistoricships.org.uk/register/974/comrades


We are planning to replace/enlarge masts on this boat and are in talks with the local shipbuilding company. The masts planned will be made of steel and rise 12 meters above the whaleback for the main (or fore) mast and 12 meters above deck for the mizzen mast (10 meters above the superstructure at the stern). Attached are some starting drawings for the sail plan and masts, scale is 1:100, so 10mm (or 2 squares on paper) corresponds to 1 meter. They are subject to change as we will also have to adjust the sail plan for balance.

The main section of the main mast will be 168mm diameter and 12mm thick with the mizzen perhaps slightly smaller or equal.


The masts will replace the old ones and the placements will remain fixed as there would be too much restructuring required to get them into their optimal positions for a ketch rig. Compromises and experimentation are expected, this is also a motor vessel, the sails will be only auxiliary.


The main mast is currently stepped on the whaleback and supported underneath by a steel H frame which sits on the deck supported by a wooden beam reinforced with a steel plate.

The Mizzen is currently stepped on the steel structure which forms the foundation for the wheelhouse.


The question we are facing is in the reinforcements of the mast steps and mast partners. How much and what is needed to reinforce the areas where the masts will attach to the boat. For now the plan is to step both masts on the deck, with the whaleback providing support as a mast partner for the main mast and the superstructure at the stern for the mizzen mast. I would like to hear your opinions and ideas for this and any guidance, direction or source of information for proper planning of this modification.


I attached plenty of photos which will hopefully demonstrate the existing structure.


Reinforcements will be most likely made of steel as the local shipbuilding company specializes in aluminium/steel boatbuilding.

I can provide more details or clear any confusion as needed.

Thank you for your suggestions and advice.

 

Are you allowed to modify a historic ship?

 

No idea, but from what I understand it is in private ownership and the owner is not getting any compensation or anything for it. They actually do not even have information on the website who exactly is the owner.

I am merely helping on the project.

 

I think the first step is to find out if the modification is legal.

 

I think it is a bit too late to ask if modifications are legal because the boat has already been heavily modified. The whaleback has been extended, there's a whole new superstructure behind the wheelhouse and where there was a fishhold is now a big aluminum box together with an aluminum bathtub planned.

But I get your point, I have not thought of it like that, if the boat is in some way protected because it is on that list of historical ships. Maybe it should be removed because of all the modifications.

 

Don't worry about this boat being on a UK Register of Historic Ships. It does not stop you doing anything to the vessel. The boat is not very old or very special (hundreds of Scottish fishing vessels of that type were built back then). Even into the early 1970s some of them carried gaff rigged sails on the mizzen mast (see attached images). However, your proposed masts and sails are much taller/bigger, so you will need to take account of better foundations/support for the masts, as well as the stays and the stability of the vessel. These Scottish motor fishing vessels of the 1950s were still closely related to their sailing predecessors so they can carry sail. But you (or someone) needs to check you have enough ballast low down.