No two vessels’ stability characteristics are the same.
Some vessels have similar stability but the stability of one vessel is never identical to another. Even so-called “sister” vessels will likely have different stability features.
The specifics of a vessel’s stability are determined by aspects such as hull form, displacement, freeboard, centre of gravity and vessel operations. For fishing vessels, operations would include such things as amount of fishing gear carried, where it is carried onboard, how fuel oil and fresh water are consumed, types of fisheries prosecuted and catch limits.
Modifying fishing vessels is very common these days, particularly with our diverse and evolving industry. Modifications to all fishing vessels, regardless of size, are required to be completed in accordance with Transport Canada Fishing Vessel Regulations.
It is also expected that the work will be carried out using accepted boatbuilding procedures and techniques and be completed by experienced and qualified individuals. This is most often the case, but not always.
Before proceeding with any major modification to a vessel, its always a great benefit to consult with a naval architect who can provide proper guidance on the rules and regulations to be followed, determine risks to the vessel and provide drawings and other documentation that may be required.
Anytime a vessel is modified, the stability features will be affected, sometimes in a positive manner but also sometimes in a negative manner. Modifications often include things like stern extensions, bulbous bows, refrigerated sea water (RSW) and live wells, adding or removing a shelter deck, modifying the wheelhouse, adding items like stabilizing fins, A-frames and deck cranes and changing the watertight integrity of the hull and decks.
Sometimes owners may feel they are improving the safety and stability of their vessel when in actuality, the opposite may be true.
Prior to proceeding with any major modifications, the stability of the vessel should be assessed by a qualified person. The benefit of this is that you will know in advance of making a large financial and time investment if your plans will result in a modified vessel that will meet some accepted stability standard such as Transport Canada or International Organization for Standardization (ISO).
Consulting with a naval architect prior to proceeding with a major modification can often save you thousands of dollars in time and materials. The naval architect can guide you on the appropriate size of structure, materials to use, effective building procedures and techniques and the rules and regulations you need to comply with. This will ultimately result in a better end product and eliminate the potential of having to redo work later if inspected by Transport Canada.
The safety and sea worthiness of a vessel is ultimately the responsibility of the owner. Receiving proper guidance before and during a major vessel modification will not only save you money in the long run but will also improve the safety of your vessel and crew members.
By Rick Young, Contributor
Rick Young is a Naval Architect and Director with TriNav Marine Design.