Can I change or scale a plan?

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Can I change or scale a plan?

Post by jacquesmm »

One of the major advantages of building your own boat is that you can customize your boat to fit your preferences. To change seats or lockers size or location is easy but beware of hull and structure changes or scaling. They may have unexpected consequences.
Keep some important points in mind when making changes:
- the structure like bulkheads and stringers spacing must be respected: never completely remove a frame, leave at least 3" all around.
- you can not change the materials specifications: the boats are designed with a safety margin and are strong.
- if you add or move components, try to keep the center of gravity as designed and the weight within reasonable limits.
- to enlarge or reduce the boat´s size by 10% is possible but will have serious consequences on the Bill OF Material and plywood nesting. Please read this about scaling:

If you require more customization, please post on the forum.
Many modifications that look simple at first often require an almost complete redesign.
Some design modifications are susceptible to become plan options that we can add to our stock plans. For example, the addition of a cabin to the PG25 became a stock plan. The rounded chine on the FS18, the longer pilothouse on the TW28 etc. all started as builder's requests for customization and became plan and kit options. In that case, the designer will modify the plans at no charge but this is rare and you must be very patient, we have a long list of designs waiting. You will have to wait several months.
In other cases, changes are not possible without extensive design work. This requires modeling and drafting work that must be paid at the same rate than local tradesmen (mechanics or plumbers), $ 100.00/hour.
Scaling a small boat can easily take 10 hours for the modeling, hydrostatics and scantlings plus another 5 hours of drafting, 15 hours total. Scaling a large boat can take 200 hours.
Even if we accept such a commission, a redesign will take several months.
Jacques Mertens - Designer


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