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-   -   Lead 'boot' - yes/no? (http://www.sailnet.com/forums/general-discussion-sailing-related/84707-lead-boot-yes-no.html)

micheck 03-07-2012 04:27 PM

Lead 'boot' - yes/no?
 
One additional question and then I will go in a corner and think!

I am 'considering' adding a lead 'boot' to the bottom of my fin keel; this would serve as a sacrificial element protecting my fiberglass keel with internal balast and would provide additional righting moment that would help 'stand up' the boat. I am looking at an additional 500# on a 12000# sailboat with a current ballast of 4000#.

I have, however, read that standing a boat up with additional balast is a good thing in strong winds, it is detrimental to the performance in light winds. I'm confused - I thought that standing up a sailboat was a good idea. Good/bad - Yes/No - Why?

Lake Superior Sailor 03-07-2012 05:01 PM

Re: Lead 'boot' - yes/no?
 
I would guess it would depend if you need it or not, My boat came with A-4 cast iron motor & I have changed it to YMS 8 aluminum motor, so I am light in rear & need to load more to the back to keep my water line flat & mast rake right. How did you plan to add this ballast boot to your boat?..Dale

SlowButSteady 03-07-2012 05:33 PM

Re: Lead 'boot' - yes/no?
 
Adding weight to the bottom of the keel will give you the greatest righting moment for a given weight. However, the weight will also lower your boat (i.e., raise the waterline) that much more, thus increasing the wetted surface area. As the hull moves through the water the relative contributions of wetted surface area (i.e., skin friction) and induced turbulence (i.e., form drag) change with increased speed. At low speed wetted surface area is the largest component of total drag, while at high speed turbulence increases dramatically and becomes the largest component of drag. So, by increasing the weight at the bottom of the keel you'll be increasing drag at slow speeds because you will have increased wetted surface area. But, at higher speeds the boat will heel slightly less, thus probably producing less turbulence, and be have slightly less drag (as long as you haven't added so much weight that the bottom of the transom is underwater, thus producing even more drag).

The best bet is usually to stick to the designed displacement of the hull. The designer probably put a lot of thought and effort into figuring out how much ballast was needed. Most folks (yours truly included) have more than compensated for any weight savings by accumulating all manner of junk on their boats. IF you have removed the engine, or replaced it with a much lighter one (or saved a significant amount of weight on the boat in some other fashion), THEN compensating for the difference MIGHT be appropriate. Otherwise, I would just leave it be and save your money for new sails, or somesuch.

All that being said, I used to own a boat, the Victory 21, that was built with an optional bulb on the bottom of the keel (mine had the bulb). The consensus was that V21s with the bulb were better sailers than those without. A V21 is a pretty light, pretty narrow, boat either way. My guess is that in light air the boats without a bulb would have had the edge. However, I sailed my on SF Bay, where the extra righting moment was often much desired.

micheck 03-07-2012 05:36 PM

Re: Lead 'boot' - yes/no?
 
I was visualizing a 'C' shaped lead channel (with the open part of the 'C' facing upward); I would bolt it through the existing fiberglass keel and existing lead ballast

What about thoughts on aiding survival on grounding?

deniseO30 03-07-2012 05:39 PM

Re: Lead 'boot' - yes/no?
 
Quote:

Originally Posted by micheck (Post 841610)
I am 'considering' adding a lead 'boot' to the bottom of my fin keel;

Ok :D who doesn't like the boat "tipping"? Hmmmm? It took 2 season for me to get used to it myself. :cool:

How does one go about making and attaching a "boot" to a keel?

Jus wonnering....

QuickMick 03-07-2012 06:02 PM

Re: Lead 'boot' - yes/no?
 
what boat are you considering adding this to? just saying it seems a lot of effort/cost (virgin lead?)/engineering for integrity etc to justify... just get a new boat...

if you stick with the idea maybe consider the bulb keel as an addition that may be a wee bit more already proven by current designs.

Only wondering if you are making a purse out of a sows ear....
good luck

oh... you could always buy a cat :eek:


hate to say, but this just sounds wonky... seems trollish, but I may be off base as you have posted more than twice. In any case, I wish you the best with your home brew C shaped lead keel add on project

SlowButSteady 03-07-2012 06:11 PM

Re: Lead 'boot' - yes/no?
 
Quote:

Originally Posted by micheck (Post 841654)
I was visualizing a 'C' shaped lead channel (with the open part of the 'C' facing upward); I would bolt it through the existing fiberglass keel and existing lead ballast

What about thoughts on aiding survival on grounding?

So you would then have a presumably watertight keel with several holes drilled through it? Even if it did nothing else, a hard grounding is likely to jiggle those bolts enough to let water penetrate into the keel (if they weren't leaking already). Like I said, it's probably best to assume the designer knew what he was doing in the first place, and avoid hard groundings. A good depth sounder must be a small fraction of the cost of this keel project you're contemplating.

QuickMick 03-07-2012 06:18 PM

Re: Lead 'boot' - yes/no?
 
Quote:

Originally Posted by SlowButSteady (Post 841674)
Even if it did nothing else, a hard grounding is likely to giggle those bolts enough.

THATS WHAT IVE BEEN DOING WRONG!! All these years Ive been asking for the jiggle, and all they did was giggle!!! :p

SlowButSteady 03-07-2012 06:23 PM

Re: Lead 'boot' - yes/no?
 
Quote:

Originally Posted by QuickMick (Post 841679)
THATS WHAT IVE BEEN DOING WRONG!! All these years Ive been asking for the jiggle, and all they did was giggle!!! :p

Oops

fallard 03-07-2012 06:25 PM

Re: Lead 'boot' - yes/no?
 
micheck: If you want to "stand up the boat", have you made sure your sails are in proper shape and that you are good at knowing when to reef? Sails that are stretched out--not necessarily obvious to the casual observer--will make it more difficult to go to weather and have you heeling more than necessary.

It might be worth the effort to check your speed made good (with a GPS) before and after reefing. You may discover that you have not reefed as soon as you might. In our case, my better half will remind me that we aren't going any faster at a heel angle of 20 degrees than we would at 15 degrees with a reef in. BTW, my boat is in the 12000 lb displacement category as well.


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