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bulb bow

1911 Views 2 Replies 3 Participants Last post by  Jeff_H
advice needed about bulb bow

i want to build FRP fishing vessel 19m is it advisable to make bulb bow
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No offense, but if you are going to build a 62 foot fiberglass boat, you should really take a few semesters of boat design classes or avail yourself of the services of a naval architect, and not just ask questions like that on an internet forum. Remember "I read it on the internet" is as scientific as "I heard it on the telephone".
I strongly but respectfully agree with JGeisinger's points above but to answer your question, the answer is 'No', bulb bows do not belong on monohull sailboats of that size or on most multihull sailboats of that size either.

You call simply call this a fishing vessel, which is too loose a description to tell what your plans are. So while there may be a reason to use a bulb bow, at 62 feet it is pretty unlikely that a bulb bow makes sense if this is a sailing vessel and even if it is not.

There were a lot of experiments with bulb bows on sailboats back in the 1970's and they were not found to offer any advantage and to offer a number of major disadvantages in heavy going and in light air. Unlike ships, sailboat bows have a variety of functions including tracking and preventing leeway, and operate at the interface between air and water, sometimes above, sometimes below, and often exposed to the full force of waves.

The current thought on designing bows that offer a seakindly motion, low resistance, reduce spray and greenwater aboard, and which help with leeway and tracking is to use a fine bow which is the opposite of using a bulb bow.

The reason that bulbs work on ships complex but is partially related to their slenderness, slab sides and comparatively blunt bows, solid state water flows, and the typical operating condition of minimal wave impact on the bulb.

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