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Keel Shortened

2K views 6 replies 6 participants last post by  SloopJonB 
#1 ·
A friend owns a Peterson 33 sailboat and says the previous owner removed 18" (appx 400lbs-500lbs) from the keel. He did this to reduce the draft to 4'8" so he can sail more places in the Florida Keys and Bahamas. He says he has sailed in up to 30kt winds with no adverse effects. I'm wandering how this keel reduction has affected the Peterson's stability, righting moment, safety factor and tenderness? Did he screw it up or is it still a useable sailboat? Any and all inputs welcome. Peterson specs: LOA:33.0'; LWL: 26.5'; Beam: 10.42'; Draft (original):5.83'; Disp: 9000lbs; Ballast: 4000lbs
 
#2 ·
Unless the Previous owner had a custom bulb keel made, I would say he took a decent boat and made it into something I would consider next to useless as a sailboat. Peterson 33-34's start out a little light on stability, and so cutting 14" and 10% of the ballast off, especially at the most effective part of the keel, seems like a really worse than terrible idea. If the owner really said that cutting off that much of the keel had "no adverse effects", I would wonder what else he was being disingenuous about.
 
#5 ·
She may not necessarily be ready for the scrap heap just yet, however...

As Jeff alluded to, it might be possible to breathe some life back into her, all it takes is cash...

Stability Bulbs | MarsKeel

When I swapped out my old keel for a shoal draft Beavertail that Mars made for Tartan, I gained an 8" reduction in draft, and much more ballast at the bottom of the keel... I've probably sacrificed a bit of leeway, but overall, the change was a pretty dramatic improvement in the general sailing characteristics, balance, and seakindliness of my old tub...
 
#4 ·
We have an Abbott 36 in our marina that had a similar chop job done, but with the advice of an NA... they also shortened the rig at the same time. She seems to sail alright, is actively being raced locally, but clearly isn't the same boat as the original.

Hard to believe that there have been no 'adverse effects' in this case.
 
#6 ·
Jon is exactly right, with care it is possible to design a custom bulb keel that retains most of the performance characteristics of a slightly deeper fin. By improving flow patterns, placing more of the keel in undisturbed flow, adding a bulb and so on, it should be possible to mitigate much that is lost when changing to a shallower draft keel.

But as I read the original post, the depth of the keel was reduced from 5'-10" to 4'-8" and the ballast weight went from 4,000 lbs to somewhere between 3500 to 3600 lbs.

There are also structural technical issues with shortening the keel that much. Most boats of that era had 'J' bolts that were cast into the lead rather than keel bolts with nuts and washers. The hooks on the bolts 'nest' with the longest ones extending almost to the bottom of the keel. If you simply cut off that much of the bottom of the keel you risk cutting at least one of the keel bolts if not all of them.

So while Jon is 100% right that the boat may not be ready for the trash heap, unless there is a custom designed keel already, then the keel itself probably is, and a new keel is worth almost as much as that whole boat.
 
#7 ·
Simply put, he took something on the order of 2500 Ft/Lbs of righting arm out of the boat. It would be like hoisting a couple of 5 gallon pails of water to the masthead before going sailing.
 
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