Agreed. Stock plans should only be modified with great care.
That said, working from a lines plan is a whole different ball game. When planning the design of Nereid, we started from a wholesome design, figure 72 in American Small Sailing Craft. I have had three fiberglass versions of this boat, all built by Jim Thayer. Each was developed from the previous one around the same basic hull. While I enjoyed these boats, they had several parameters I felt needed changing for my needs.
The current hull is slightly longer and 6" narrower than the previous boats. All four are/have been rigged to sail, with modifications to the sails and rig from the predecessors.
As mentioned in the article, the length was simply changed by moving the stations a little further apart. Working from the somewhat out of focus table of offsets in the book, we were able to develop the beam measurements at each station. We decided to maintain the original hull depth at each station in the interest of seaworthiness. All sailboats heel and this one will certainly heel more than the original when under sail due to the decreased beam.
The only disappointment I have is that the boat is heavier than my original concept.
Already two people who have seen her under construction have asked for permission to use the molds for their own boats. I believe we have a winner here.
This is a very important article. As a boat builder, boat building instructor and sailor I often hear of people wanting to stretch this or that, increase lumber dimensions and more and most times it just doesn't work as the designer specified. Now this said I often make modifications to boats I build straying from the design sheets but these to date have never been dimensional changes, instead experienced based set up changes in cockpit layout, hardware, sail rigs etc. I mock up substantive changes in cardboard or 1/8" inexpensive sheet plywood (paneling or door skin) before I commit. to any cockpit or interior change. I try it out. With respect new builders be careful, beware. Best to consult with the designer on major changes or simply select another design.
Always plenty of food for thought! I would suggest, however, that one does need to be quite clear on their needs for space in a boats interior. Mocking up as best one can, while going over study plans can be critical. In boats the size of the ones we usually talk about, inches matter. This is particularly important for those of use whose size is not average in one aspect or another. Sitting headroom, and the ability to turn over in a bunk can really ruin a guys day if not confirmed before the build. Mocking up is rarely spoken of but very important if the numbers are close to minimal. I would recommend these things be discussed with designer before purchase of building plans.
Who is (was) Ken Hankinson? See https://www.glen-l.com/blog/ken-hankinson-will-live-on-in-our-hearts-and-in-his-designs/?srsltid=AfmBOopm6Zaw5D2L60b_tE72ZC6xDdXYNUL6tgihgS-V6IXkb6WCi3gy. Thanks for posting, Josh.
Agreed. Stock plans should only be modified with great care.
That said, working from a lines plan is a whole different ball game. When planning the design of Nereid, we started from a wholesome design, figure 72 in American Small Sailing Craft. I have had three fiberglass versions of this boat, all built by Jim Thayer. Each was developed from the previous one around the same basic hull. While I enjoyed these boats, they had several parameters I felt needed changing for my needs.
The current hull is slightly longer and 6" narrower than the previous boats. All four are/have been rigged to sail, with modifications to the sails and rig from the predecessors.
As mentioned in the article, the length was simply changed by moving the stations a little further apart. Working from the somewhat out of focus table of offsets in the book, we were able to develop the beam measurements at each station. We decided to maintain the original hull depth at each station in the interest of seaworthiness. All sailboats heel and this one will certainly heel more than the original when under sail due to the decreased beam.
The only disappointment I have is that the boat is heavier than my original concept.
Already two people who have seen her under construction have asked for permission to use the molds for their own boats. I believe we have a winner here.
This is a very important article. As a boat builder, boat building instructor and sailor I often hear of people wanting to stretch this or that, increase lumber dimensions and more and most times it just doesn't work as the designer specified. Now this said I often make modifications to boats I build straying from the design sheets but these to date have never been dimensional changes, instead experienced based set up changes in cockpit layout, hardware, sail rigs etc. I mock up substantive changes in cardboard or 1/8" inexpensive sheet plywood (paneling or door skin) before I commit. to any cockpit or interior change. I try it out. With respect new builders be careful, beware. Best to consult with the designer on major changes or simply select another design.
Always plenty of food for thought! I would suggest, however, that one does need to be quite clear on their needs for space in a boats interior. Mocking up as best one can, while going over study plans can be critical. In boats the size of the ones we usually talk about, inches matter. This is particularly important for those of use whose size is not average in one aspect or another. Sitting headroom, and the ability to turn over in a bunk can really ruin a guys day if not confirmed before the build. Mocking up is rarely spoken of but very important if the numbers are close to minimal. I would recommend these things be discussed with designer before purchase of building plans.