Join Date: Sep 2011
Location: Liberty Landing
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Re: Conversion to Keelboat
Well if it helps Richard, a Centerboard (AKA swingkeel) will be far less efficient than a drop bulb keel, but is just as adequate on a non- sporty boat. It will take up much more interior space, and will be difficult to secure in the down position. It is also far more difficult to make IMHO. It will kick up if you hit bottom that is probably its only advantage.
The drop keel can be easily constructed in a way that it won't slip up into the slot unless you release it so if you turtle it can easily be secured and won't slip back into the case.
250-400# seems like way too much lead for a ballasted dinghy with a deep bulb keel. That i-550 is 18' long, 880# displacement with a 160# bulb. You should be aware that there is an argument against ballasting any dinghy, in that sometimes performance really suffers due to the extra weight, and proper crew placement can be more effective than a proper keel on these small boats.