# Shoal draft keel versus regular fin keel



## GBurton (Jun 26, 2007)

Is there a distinct tradeoff in performance between the two if they are on the same model boat?

I assume that the weight is the same except with the shoal draft version it is spread out along the hull instead of below the boats center of gravity.

There must be some difference in the "moment of inertia" between the two but is it enough to make a big difference?

I certainly do not need a shoal draft boat but there is a very clean looking one for sale that I'm looking at.

Thanks for any knowledgeable input.


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## sailingdog (Mar 19, 2006)

Often shoal draft boats will have a slightly heavier keel to make up for the shorter lever arm. Generally, the deeper draft fin keel will also have slightly better to windward performance.


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## killarney_sailor (May 4, 2006)

*Check PHRF ratings to compare*

I looked at a couple of boat's rating with deep keels and shoal keels and the difference seemed to be 6 to 9 sec/mi. Not a huge difference really.

I would prefer the deep draft version except for docking. I am looking for a boat in the 40 - 43 foot range for Lake Ontario (initially) and anything beyond 6' is a problem. Hence a shoal draft version would be the choice here.


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## GBurton (Jun 26, 2007)

Thanks....... I'm enjoying looking at boats!


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## Cruisingdad (Jul 21, 2006)

GB,

Regardless of what the numbers say, my experience is that fins ALWAYS perform better. Period. That being said, I am a fan of wing and sholad draft boats because of my cruising grounds. A fin on the same boat would keep me in the dock. Wings are also tougher to get out of the mud/shoal, but the argument could (COULD) be made they are less likely to get stuck in the first place.

In the end, it will all come down to the cruising grounds. Buy a boat where draft will be a minimum issue, or no matter how good your fin sails when moving, it will be wortless at the dock.

Did that make sense?? Others may bave other opinions.

- CD


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## GBurton (Jun 26, 2007)

CD -

Yeah, makes sense.

Thanks


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## BarryL (Aug 21, 2003)

Hello,

I think it's a little more complicated than just your cruising grounds. If you are buying a used boat, and you find a great one, but it has a shoal draft, do you skip it or buy it even if you don't NEED shoal draft? If you are a racer you skip it. If not, then what?

Do you ever anchor out, or anchor and swim off the boat? The shoal draft will allow you to get closer to shore. 

If you really value performance, the shoal draft won't point as high. Is that going to bother you?

For me personally, my last boat had a deep draft (5' 2"). My current boat has shoal draft (4' 6" or so). My last boat would point higher. My current boat allows me to anchor 20' off the beach. 

I wasn't looking for a shoal draft boat. In fact, the listing on my boat stated it had the fin keel (5' 6" draft). When the boat was hauled for the survey I told the surveyor that the keel looked like the shoal draft version (wider and shorter). He took his tape measure and measured it at 4' something. The owner said something was wrong, she KNEW it was the deep keel. The surveyor gave her the tape measure and said "measure it yourself." It IS the shoal draft. 

I still don't know which one I like better, but I have the shoal draft.

Barry


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## paul77 (Jul 5, 2007)

*change the keel?*

As a follow up to BarryL's comment about it not necessarily being an option for used...

Given that many boats offer shoal and deep draft versions, would it be possible to change the shoal version to a deep draft version? Would that prohibitively expensive? I understand the rudder may need to be changed out too.

This is assuming it's not poured in place, and is rather attached with keel bolts, and that the ballast is the same type of material between fin and shoal draft. (in order to stay within the original manufacturers design parameters).

It seems totally nuts, but this is sailnet, so maybe someone has tried it?


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## SanderO (Jul 12, 2007)

You should be able to point a bit higher as the deep keel acts like a lifting foil or so the mythology goes. 

I would think that the shoal draft might be a bit more tender and being a bit longer track a bit better and turn a bit slower on tacks. But the differences in performance are probably so small that the advantages of the shoal draft outweigh all the advantages of the deep draft.

And you need a shorter ladder when you are at the boat yard!

jef
sv shiva


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## paul77 (Jul 5, 2007)

Maybe in NY.. here in the northwest there are really no advantages to having a shoal draft. Being higher up in the yard means a taller ladder, but it means you get a nicer view too!

From what I understand the differences in performance are more than minor though I'm sure it varies wildly from boat to boat.


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## TSOJOURNER (Dec 16, 1999)

Basic physics - a little weight further out has leverage to equal substantially more weight closer to the fulcrum point.


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## TSOJOURNER (Dec 16, 1999)

> Given that many boats offer shoal and deep draft versions, would it be possible to change the shoal version to a deep draft version? Would that prohibitively expensive? I understand the rudder may need to be changed out too.
> 
> This is assuming it's not poured in place, and is rather attached with keel bolts, and that the ballast is the same type of material between fin and shoal draft. (in order to stay within the original manufacturers design parameters).
> 
> It seems totally nuts, but this is sailnet, so maybe someone has tried it?


It has been done. Mars Metal is a good company to contact to explore the option. The keel itself may not be as expensive as having it shipped to you, lifting the boat, getting rid of the old one and refinishing the area...

http://www.marsmetal.com/newpages/keelhome17.html


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## tommyt (Sep 21, 2002)

I am sure that people have changed out keels....but why? 

On my boat, which is a 34' shoal draft, the keel weighs 5,200 pounds. Anyone price 5,200 pounds of lead formed into a keel with bolts lately? There are way to many boats out there for sail to get into this kind of a refit. 

With new rudder, probably in the neighborhood of $20,000. Buy one with the keel you want!


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## sailingdog (Mar 19, 2006)

I'd have to agree with tommyT... doesn't make sense to swap out a keel, unless there is something wrong with it or the boat is extremely large and expensive.


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## blt2ski (May 5, 2005)

SOme of the newer 4 digit Tartans are designed such that one can change out the keel in a simple fashion. So if one were to buy a deep draft as is typically speced here in the puget sound region, and you sail to a shallower draft region, or move it too, you can get the shallower draft keel installed easy enough. Personally, I can not think of ANY advantages to a shoal draft. But that is from some one that is typically reading "---" on the depth guage! ie too deep to read! Then again, maybe if I was on the east coast, I might thing differently. I personally will take the deepest lightest keep I can get! Makes you faster to some degree, may not be a lot, but it is faster none the less!

Marty


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## TSOJOURNER (Dec 16, 1999)

You would definitely miss out on much of the really good sailing on the Chesapeake Bay with a 6 ft. keel!


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## TSOJOURNER (Dec 16, 1999)

paul77 said:


> ......would it be possible to change the shoal version to a deep draft version?


There was a guy in our yacht club who changed his fin keel to a wing keel. He would have consulted with the designer or a naval architect before he started. He did the work himself with friends helping. He cut a 2 or 3 feet off the keel, made a mold for the wing and casted it with the lead he removed, plus some more. He drilled and lagged several bolts into the fin and bolted the wing on. Major job, but do-able.


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## mikehoyt (Nov 27, 2000)

I think it really depends on your needs. I f you don't need shoal draft I would advise not to get it.

Our club is located inside a channel that at moon low is only two feet. Shoal draft is very desirable because it means waiting less time to go in and out of channel. Typical low tide is almost 4 feet so many shallower draft boats are not very affected at all.

The next point is that it all depends on the boat and the design. Research the performance of each before deciding. Even die hard cruisers who repeatedly state that "speed is not important" like to have a boat that performs well if possible. As has oft been stated here an extra bit of pointing or speed means you reach your next destination sooner ...

Several examples I have seen at our club. C&C30 mark 1. We have had two with shoal draft version and 4 with the standard fin. The "shoal" version is actually a fin but is a bit longer and about 1 foot shallower. It does not give up a lot on performance to the other C&Cs. In my mind this shoal version is a winner. Other examples are a 1990 MacGregor 26 - not shoal but a swing keel or centerboard or something. The rest of the boats had all finished our end of season fun race and that boat had not yet made the windward mark. Yet another is an ODay 27 with a stubby wing keel. Again the performance to weather is lacking.

I agree with above posters. There are enough used boats out there that it is probably cheaper to sell your boat and buy the same baot with a shoal keel than it is to change your own keel. Then there is the fact that the designers of the boats with shoal keels probably attempted to get maximum performance from that shoal keel as well as stability. A DIY keel mod would always make me nervous. The boat is designed with the keel on it. Unless you area very knowledgable naval architect I can't see chopping off 3 feet to be a good idea in any circumstance.

Buy the right boat for the area. Do the research. Then post your question here about how such and such a boat you have found and how well it is built, performs, etc ...

Good Luck!

Looking is the best part!

Mike
Full Tilt 2


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## TSOJOURNER (Dec 16, 1999)

Unless you are planning on racing a fair bit, the performance issue is not a big one. The difference between a specific boat with a shoal keel and the same boat with a fin keel is usually measured in the single digits (per mile). You need to be a very good sailor to take advantage of this.

If you like the boat - buy it and don't worry much about the keel. If it was designed to sail with a shoal keel then chances are it will work well.  BTW - a properly designed wing keel will provide slightly better off-wind performance than a fin...


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## Jeff_H (Feb 26, 2000)

I keep hearing what I consider the somewhat the misleading information that one misses out on great Chesapeake sailing with more than 6' of draft but having cruised the Chesapeake with 6'4 - 6'6 draft current boat for the past five years I see almost no difference in where I can go between my current boat and the 5' draft boat that I had before her. For many years I cruised with a boat that drew over 7 feet and they seemed to go wherever I went with my 5 feet, just more carefully. I would think that you needed to get down to less than 4 feet to see much of a difference in cruising grounds. 

The thing about deeper draft fins vs shoal draft or wing keels is that the shallower boats have a lot more drag. The difference in speed doesn't show up much in higher breezes, and so the relatively small rating difference, but in the Chesapeake with our predominantly light winds, it makes a huge difference in the number of sailing days per year that you will actually get to sail vs motor. 

Jeff


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## OrangeOwl (Jun 13, 2007)

So, here is a wierd situation; check out the S2 9.1 on yachtworld (YW# 22624-1744489) Turns out the driving reason it is approx $10k under normal asking price is that they have turned a fin keel into a shoal draft by cutting of about a foot and adding a bulb. It is reported to be a very clean job and looks ok in the pictures. My initial reaction (and 2nd, 3rd, etc.) is to run away butt.....

This boat is potentially a very good deal and the S2 has a bit more livable cockpit and interior than a J30. I'm looking at day sailing/weekending withthe wife and 2 kids, plus the random club race with some buds. I'm wondering if I should talk myself into a big drive to look it over in person.


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## TSOJOURNER (Dec 16, 1999)

> So, here is a wierd situation; check out the S2 9.1 on yachtworld (YW# 22624-1744489) Turns out the driving reason it is approx $10k under normal asking price is that they have turned a fin keel into a shoal draft by cutting of about a foot and adding a bulb. It is reported to be a very clean job and looks ok in the pictures. My initial reaction (and 2nd, 3rd, etc.) is to run away butt.....


This is not that unusual. In an earlier post I mentioned Mars Metals, which is a company that does this. They are known locally for the "Mars Bulb", which is a hydrodynamically designed torpedo type of bulb put on the bottom of fin keels. The weight, placement and shape of the bulb are carefully calculated based on the shape of the hull and keel.

It is my understanding that they started doing this in order to compensate for weight lost when some die-hard racers decided to modify the shape of their fins, shortening the chord in an attempt to emulate boats such as the Mumm and Mount Gay.

It has also been done for some people who have grown tired of running aground in shallow waters. I don't think you should discount the boat because of this, it would be worth researching who did it, and how much time and thought was put into it.

I would not discount this boat based on the keel alone. It looks like a professional casting...


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