# Would your keel joint survive a full speed impact?



## downeast450 (Jan 16, 2008)

I am wondering how many of us with fins bolted on feel the hull we have could survive a full force impact with something fixed.

I have no obvious signs of failure at the keel stub joint on TD. It is a 1976 Islander 28. No leaks. The visible bolts are badly rusted to the ss nuts. Outside, I can see the seam between lead and fg in places when is is on the hard and gets wet. There is no visible gap but a line appears as rainwater runs along it.

The boat is doing its job well and we would like to head a little further afield. As we study the safety of "real" cruising boats with encapsulated keels or thick aluminum hulls it makes me pause to think what I would be doing on TD immediately after hitting something fixed at speed. Would I be plugging leaks or would I have lost the keel? Is this an acceptable risk? 

Would your fin survive a full speed impact?

Down


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## Faster (Sep 13, 2005)

Define "survive".....

Few boats would suffer leakage immediately, I suspect, but the amount of damage inflicted will vary substantially depending on a number of factors. One of the largest factors will be keel material. Lead absorbs an amazing amount of energy as it deforms under impact. Iron keels do not and transfer the full forces to the hull - therefore internal damage is likely to be more significant with iron keels.

Most hulls can absorb the flexing that results with the leverage of the keel applies the rotating forces of impact into the hull. The area immediately aft of the keel is usually more affected, as the keel tries to rotate into the hull there. Solid glass hulls may flex and absorb the brunt of the impact, but generally any tabbed stringers and floors are likely to be separated from the hull, reducing structural integrity there. In extreme cases the laminate may be fractured in a way that can be difficult to determine. On a lightly built boat I suppose the narrow, pointed aft section of the keel might actually puncture the hull.... that would, of course, be bad news....

With cored hulls and their inherent stiffness, if their strength is overcome in impact then there may be delamination of the core and skins in that area as well as tabbing separation - leading to a bigger repair job. But even cored hulls are generally solid glass in that area...

The nasty part of all this is that often the damage, even if considerable, will not be particularly visible.. esp in the presence of extensive liner use. btw if you see a new crack in a liner then it's almost certain there's more/worse underneath.


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## davidpm (Oct 22, 2007)

Catalina 27' hit pretty hard going maybe 5 knots. As Faster said the keel was rotated up and aft of the keel was damaged. It was taking on water but very slowly, maybe a cup a day. Had insurance repair it.


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## tommays (Sep 9, 2008)

The joint and bolts were OK but about two feet BEHIND the keel the hull suffered pretty badly and leaked a good bit till we took down the sails and backed off the rigging

It took a rather large truckload of money as 7' keels seem to be quite the lever


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## Faster (Sep 13, 2005)

Yes - properly done these kinds of repairs can quickly run into 5 digits...

btw Tommays, that's no stock C&C... do you know who did the keel??


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## celenoglu (Dec 13, 2008)

Two different casesfor cast iron keels:

1. The boat hit rocks with speed of 5 knots. The keel was not damaged but the hull was broken at the aft end of the keel. They managed to get to the marina which was very near and immediately taken to dry land.

2. The boat hit rocks exceeding 6 knots. Ribs and leg bones of different crews were broken due to immediate stopping of the boat. No water inside the hull and no damage to the hull. They sailed approximately for 50 miles. Only the front part of the keel was broken. The keel only lost 15 -20 lbs of metal from the front part.

The answer is "it depends".


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## tommays (Sep 9, 2008)

The orginal owner had a few dollars to throw around and spent them on the boat and then went to the next stage and hired Britton Chance who did TWO keels(he did not like the first one ) a rudder and the current double spreader rig 

At some point he moved on and it fell into a sad state and my friend brought it back to life 


The boat has a PHRF of 117 compared to the stock 35 and is still competive if we point the right way


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## downeast450 (Jan 16, 2008)

I am encouraged! Ha!

"Survive", as in make it to a port. 

The only time I have hit anything with the keel was loading it onto a truck at haul out. I bumped the wooden cross beam / keel support as I approached the Brownell trailer. The trailer was not deep enough. I was barely moving and the jolt gave me pause. It is a 3000 lb. chunk of lead bolted to about 4000 lbs of boat and it came to a sudden stop! There was a little momentum involved but no opportunity for a rotational moment as the trailer's pads were high enough to brace the hull. It made me wonder what would happen if we really smacked something motoring into an unfamiliar cove in Newfoundland.

Thanks for all the good information.

Down


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## Jeff_H (Feb 26, 2000)

As has been said, very few boats can withstand a full speed collision with an immovable object such as a rock. I apologize that I had written this for an earlier discussion on this topic and so it may not be completely relevant. 

With a bolt-on keel, the good news is that if the boat does not sink, a nearly good as new repair can usually be made. The bad news is that this can often involve removing the keel, cutting away all damaged glass (which may include the internal framing as well, doing a careful rebuild. It is rare that the bolts themselves fail and when they do, it is usually a case where corrosion has badly reduced the diameter of the bolt. 

Lead keels are generally considered better the cast iron in these types of collisions because the lead can absorb some of the shock and therefore impart less force into the hull and keel attachment structure. 

This kind of full speed impact with the proverbial immovable object is especially devastating to most encapsulated keels. In a full speed collision, the fiberglass itself comes into contact with the object and is generally crushed and deformed. This allows the ballast keel to be pushed upward into the bilge membrane. Unlike most bolt on keels, encapsulated keels rarely have the internal structure to absorb and distribute these impact forces. 

Successfully rebuilding this kind of damage is much more difficult. The ballast should be removed, the encapsulation envelope checked for internal damage, and repaired, the ballast bonded back in place, and the internal bilge membrane rebuilt. It is very hard to get this back to being a like-new repair. 

Owners and insurance companies often elect to merely repair the point of contact on the encapsulation envelope. That often is not an adequate repair. The bond between the ballast keel and the keel envelope, is a part of the structure of the boat. It allows the load of the ballast to transfer and be distributed into the hull, and is the reason that encapsulated keels often get by with minimal internal framing. In the kind of grounding being discussed, that bond between ballast keel and the shell is generally broken resulting in a boat with substantially less resistance to the next hard grounding, with a greater tendency for blisters due to moisture trapped in the encapsulation, and greater tendency toward flexure and therefore fatigue.


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## davidpm (Oct 22, 2007)

Jeff_H said:


> Owners and insurance companies often elect to merely repair the point of contact on the encapsulation envelope. That often is not an adequate repair. The bond between the ballast keel and the keel envelope, is a part of the structure of the boat. It allows the load of the ballast to transfer and be distributed into the hull, and is the reason that encapsulated keels often get by with minimal internal framing. In the kind of grounding being discussed, that bond between ballast keel and the shell is generally broken resulting in a boat with substantially less resistance to the next hard grounding, with a greater tendency for blisters due to moisture trapped in the encapsulation, and greater tendency toward flexure and therefore fatigue.


this is very scary. How do you survey for this, or do you just pass on all encapsulated keels?


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## beachmont (Sep 18, 2011)

All this talk is about the keel and hull the standing rigging takes a beating too


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## Jeff_H (Feb 26, 2000)

davidpm said:


> this is very scary. How do you survey for this, or do you just pass on all encapsulated keels?


Personnally, I do generally pass on encapsulated keels, preferring a bolt on keel assuming that the connections are properly engineered. That is a very big assumption, since the design of keel connections vary widely and some are just not as good as others. But also, bolt on keels require more long term maintenance, ideally being removed periodically so the keel bolts can be inspected and the joint recaulked. To me this is a matter of a trade off between something which can be maintained but which requires more maintenance vs something which is lower initial maintenance but which ultimately cannot be rebuilt properly.

But if I were to consider buying a boat with an encapsulated keel, I would want to check for delamination. A good surveyor, let alone a reasonably astute amateur can tap out a keel encapsulation envelope for delamination. A large enough delaminated section to be problematic is pretty easy to hear, let alone feel.

About ten years ago, during in an earlier discussion of this topic I went through a yard, tapping on encapsulated keels with my bare knuckles. I took notes and don't recall the exact percentage, but my recollection is that roughly half had delaminated areas that were larger than 18" in diameter and some where completely delaminated and would flex when simply pushed on. During that period I spoke to a couple yacht designers and a marine composites engineer who did work for yacht designers, and the sense was that depending on the size of the boat, an 18" dia. delam was at the point where it impacted the ability of the boat to safely absorb the next impact.


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## mgiguere (May 22, 2004)

Hit a rock at 5 1/2 knots cutting a corner to closely years ago rounding into Marblehead harbor from Peaches Point. No leaking, no damage. Still have the same boat 15 years later...Chris Craft Apache 37 sloop with a cast iron fin keel bolted to the hull. When I pulled the boat that fall, there was a very small chunk missing off the leading edge that I fared smooth. 

BTW, great sailing day across the Chesapeake Bay yesterday (New Year's) from Galesville.


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## Minnewaska (Feb 21, 2010)

There is a J-54DS for sale up on Lake Erie that reportedly hit a sandbar at full throttle. She made it to port, but I'm told had substantial damage that has since been repaired. Unfortunately, given the glut of boats on the market, I'm sure she will be the last 54DS to ever sell.


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## killarney_sailor (May 4, 2006)

*You had the repair done in China?*



tommays said:


> It took a rather large truckload of money as 7' keels seem to be quite the lever


It looks like you paid with a (small) truckload of yuan.


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## davidpm (Oct 22, 2007)

Jeff_H said:


> But if I were to consider buying a boat with an encapsulated keel, I would want to check for delamination. A good surveyor, let alone a reasonably astute amateur can tap out a keel encapsulation envelope for delamination. A large enough delaminated section to be problematic is pretty easy to hear, let alone feel.
> 
> About ten years ago, during in an earlier discussion of this topic I went through a yard, tapping on encapsulated keels with my bare knuckles. I took notes and don't recall the exact percentage, but my recollection is that roughly half had delaminated areas that were larger than 18" in diameter and some where completely delaminated and would flex when simply pushed on.


I'm assuming that tapping on good keel sounds solid and hurts and delaminated sounds hollow and does not hurt as much.

18" seems like a very generous allowance. Wouldn't any delamination probably mean water egress and water, at least salt would mean more delamination as freezing and rusting continued?
How exactly are these keels filled. I've heard of chunks of iron or lead set in concrete was one method.
In old Catalina 30's they had a plywood shoe in the bottom of the stub keel. The top of the glass in the bottom of the bildge has to be removed, the plywood dug out and replaced with glass.
Would a repair on a encapsulated keel be simililer in that the bottom of the bildge would have to be removed but then the whole keel would have to be excavated?
It sounds like wet deck core work. Probably not expensive to do ones self but a really big nasty long job.


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## smurphny (Feb 20, 2009)

In looking at the encapsulated keel with the bloody nose above, it seems that there is a relatively small cover of glass on a long lever. As I discussed in previous posts, I hit a rock (or something) doing full speed under power, 6 knots or so, with my old Alberg. It was a couple of years ago on Lake Champlain when the lake was terribly low. Talk about Aw S%^t moments! It took a good chunk out of the glass, which is > 2" thick at the bottom of the keel. I was surprised, in doing the repair that the lead in these type designs is seated on top of some 3/4" balsa core material. The balsa, I'm sure, distributed the impact by depressing and allowing the glass to break rather than having the impact go directly into the lead. It was also easy to just dig out and replace some of the balsa with new to regain the hull shape. Having to work overhead, the repair was a PITA but not catastrophic nor very expensive. It was just time consuming building up that many layers of glass (heavy roving mostly) feathered out 20" or so from the gouge. There was no sign of any stress or distortion in the bilge above the impact and the sloped angle of the keel no doubt allowed the boat to ride up and over whatever I hit. (I think it was probably the buoy mooring which I was too close to.) So, I guess the type of encapsulated hull design has a lot to do with what happens when meeting a rock.


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## hellosailor (Apr 11, 2006)

down, the I28 is built like a brick *house, it isn't easy to break one. But AFAIK there is no keel designed to take hard impacts without structurl damage to the boat. Either you tear the keel off, or the hull lets go, the amount of force involved in a "head on" collision is going to wrinkle the boat. Even if you kept the keel on, the rig would probably be damaged and the bulkheads come untabbed--on any boat.

Hit a concrete divider with a Mercedes, and you'll still total the car. Build the car strong enough to break the wall, and you've got a tank instead of a car. Tanks don't sail well. And the I28 doesn't do so well in ghosting conditions, as it is.


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## downeast450 (Jan 16, 2008)

Hello,

I am impressed with how the I-28 is built. You are right. The 1/2" thick steel keel stub plate is an indication of that. This thread has opened my eyes to the distribution of force one should expect when hitting a solid obstruction with the keel. It isn't a very heavy boat at 7,000 pounds. Almost half of its mass is the lead and that is raked backward at a fairly good angle. "Some damage" should be expected if you smash into something but I will expect to "survive" an accident like that if it ever occurs. There would certainly be a tendency to "ride up" on impact. The likely hood of the keel breaking away is probably very small.

It isn't impressive until things start to blow then the I-28 is a special little sailboat.

Down


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## msmith10 (Feb 28, 2009)

Minnewaska said:


> There is a J-54DS for sale up on Lake Erie that reportedly hit a sandbar at full throttle. She made it to port, but I'm told had substantial damage that has since been repaired. Unfortunately, given the glut of boats on the market, I'm sure she will be the last 54DS to ever sell.


I know the boat. She didn't hit sand-- she hit rocks under power at considerable speed. Impact was enough to tear the engine and generator off their mounts. Yes, it was repaired, at over $200k in costs, but it's not a boat I'd buy.
Correction: It may not be the same boat. There is a Yachtworld listing that is not the boat I'm referring to.
Same story, though.


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## hellosailor (Apr 11, 2006)

"until things start to blow "
Yes, the I28 gets outright talkative at 40 knots, you can hear each piece of the boat as it hands off the load from every surge down through the mast to the keel. Kinda like a big dog walking through a pond, shaking it all off and saying "What?" when you complain about the splatter.
Who wants to sail in under five knots anyway? (VBG)


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## Minnewaska (Feb 21, 2010)

msmith10 said:


> I know the boat. She didn't hit sand-- she hit rocks under power at considerable speed. Impact was enough to tear the engine and generator off their mounts. Yes, it was repaired, at over $200k in costs, but it's not a boat I'd buy.
> Correction: It may not be the same boat. There is a Yachtworld listing that is not the boat I'm referring to.
> Same story, though.


I am told it is one of the boats out on yachtworld. Ive never seen it, but was told the story by a surveyor that I used on mine.

I cant imagine the damage if we rammed our keel into rocks at full throttle. 40,000+ lbs at 8 to 9 kts and a dead stop in inches. Says something that it reportedly stayed afloat. It had to have been towed in, but I don't know.


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## SloopJonB (Jun 6, 2011)

Faster said:


> One of the largest factors will be keel material. Lead absorbs an amazing amount of energy as it deforms under impact. Iron keels do not and transfer the full forces to the hull - therefore internal damage is likely to be more significant with iron keels.


The designer Bill Garden said the opposite in one of his yacht design books. His opinion was that lead would crush and "form" around the obstruction and as a result, the boat would absorb the full energy of the impact. Iron, on the other hand would tend to bounce off the obstruction and not absorb the same amount of energy. He preferred iron on boats that would sometimes have to "feel" their way into anchorages.

I have seen or experienced both and I tend to agree with Garden. I hit a rock at full speed with a lead fin keel - the boat stopped dead, crew were thrown off their feet, minor injuries etc. The boat survived intact but I had an 8" square area of the toe of the keel to fill and fair on the next haulout.

On the other hand, I was looking out over English Bay one evening from a bluff in Kitsilano, watching a 33'ish wooden motorsailor motoring by fairly near shore. All of a sudden there was a very audible CLANG and the boat jumped about a foot. The skipper merely turned a few degrees offshore and just kept on truckin' - completely unruffled - no crew flying about, no drama, just an almighty CLANG, clearly audible from at least 300 yards.

I saw that long before I read Garden's book and immediately thought of it when I did - his words completely agreed with what I witnessed (and later experienced).

Also, when I was redoing the iron keel on my current boat, on the toe of the keel there were a number of 1/4" deep gouges in the toe area - the boat had been through El Caribe from New York to L.A. and had apparently hit some coral or something - 1/4" deep gouges in SOLID IRON - how much force did that take?  It left a lot less damage than the lead incurred on my old boat.

As to the OP's question, I am confident my iron keel can withstand a hard hit. It has a 1' wide, 10' long flange along the top with a double row of studs spaced 10" apart laterally. For those familiar with the Thunderbird, it is not unlike how their keels are mounted. The whole thing fits up into a 1 1/2" deep rabbet moulded into the hull. The bottom above it at that point is 2" thick. On the inside, each pair of studs passes through a piece of 2" X 4" X 24" stainless channel with thick fender washers and double nuts on each stud. There are also 8" timber "floors" glassed into the bottom between every other stainless channel.

I think it can take a hit.


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## Maine Sail (Jan 6, 2003)

hellosailor said:


> down, the I28 is built like a brick *house, it isn't easy to break one. *But AFAIK there is no keel designed to take hard impacts without structurl damage to the boat. *Either you tear the keel off, or the hull lets go, the amount of force involved in a "head on" collision is going to wrinkle the boat. Even if you kept the keel on, the rig would probably be damaged and the bulkheads come untabbed--on any boat.


Coming from Maine the land of GRANITE ledges we see LOTS of boats hit rocks each year. If I had to guess I'd say in the 150 -250 hard groundings per year. I know of ONE keel the fell off over the last 20 years. It was a J Boat. In one week two years ago I watched 8 boats get hauled at the same yard for "ledge damage inspection".. I'm always perplexed how so many folks find these ledges but they do..

The worst and longest repairs I see are encapsulated keels or fins on quite lightly built boats because there can be structural damage. I once watched an Island Packet drain water from the keel encapsulation (cement) for over 7 weeks and it was still far from dry when the out of state owners hauled it away on a truck. During the time the IP was drying two or three fin keelers were hauled ground, filled, faired and re-launched..

I would have to say the a large percentage of groundings in Maine result in not much more than some dents and dings in the lead.

I had two of my customers hit ledges this summer alone and both were at full tilt and one with an SOG of about 7.2 - 7.3 knots. He hit solid granite and people aboard were bruised. The keels were mashed and the keel hull joints will be ground & faired, the lead dents fixed and they will be fine for many more years. Structural damage is non-existent on either of these boats one is an 82 Sabre 34 MKI and the other an 87 Ericson 32. Both of these boats were deep fins not shoal..

Many fin keel boats hit granite here in Maine with no structural damage and only lead dents and perhaps some cracking of the keel hull fairing putty. While some do have structural damage sinkings and keels ripping off are very rare.

These folks found the ledge and had to wait out the tide..


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## Barquito (Dec 5, 2007)

This has been an eye opening thread for me. I really don't like the idea of looking and wondering if keelbolts are rusting, and moderatly don't like the idea of replacing keel boats. Therefore, I went with an encapsulated keel design. However, I can now see the argument for bolt-on keels. What about adding a really thick 'skid plate' to the nose of an encapsulated keel?

Also, it is obvious that bigger boats are stonger, but, it seems the force of a full speed hit in a large boat would be orders of magnitude larger than in a small boat. The keel lever arm is longer, the weight of the boat is larger, and the top speed of the boat is greater. Are deep draft, heavy, big-boats built THAT strong?


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## hellosailor (Apr 11, 2006)

A skid plate only works by deflecting what it is attached to. You'd have to run it from the bow to the bottom of the keel, so you could skid up over whatever you hit. And it would have to be built and attached strong enough to allow that shift up and over. That would be a lot of weight, and you'd probably still trash the rig and bulkhead tabbing when you hit.

Easier to just stay in clear water.


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## tommays (Sep 9, 2008)

On my friends Tartan 372 when they hit the Ledge in Maine the biggest issue was breaking all four Volvo motor mounts as the motor is under the kitchen sink its a bit of chore


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## goboatingnow (Oct 10, 2008)

have a look at

Crash Test - Dehler 31 yacht - YouTube


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## DelmarRey (Aug 25, 2001)

*Oh No!*

Now I need a T-shirt that says "I survived a hard grounding".


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## downeast450 (Jan 16, 2008)

Maine,

I am amazed at that number of hard groundings / year. I spend much of the sailing season along the Maine coast and have many friends who sail here. I only know of two hard hits around MDI in the past few years. I guess I don't know as many sailors as I thought. My sailing friends are "locals". Is the carnage you mention happening to boats from "away"? There are not that many "hidden" spots if the skipper is competent.

Down


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## sailingfool (Apr 17, 2000)

downeast450 said:


> ... Is the carnage you mention happening to boats from "away"? There are not that many "hidden" spots if the skipper is competent.
> 
> Down


I would expect that the carnage for one thing, involves boats from anywhere that are doing their navigation without reference to paper charts.


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## DelmarRey (Aug 25, 2001)

sailingfool said:


> I would expect that the carnage for one thing, involves boats from anywhere that are doing their navigation without reference to paper charts.


All it takes is that simple distraction of a wife bending you ear while trying to find a gunkhole. Even if they are on charts one would have to keep their nose glued to the chart to find the ones that are a like volcano growing up out of the sea.

The one I hit, has been hit so many times that is a joke for the locals. It hada marker but the powerboaters kept running over it. Not big enough, I guess.

Find this on on your charts 50º 3.957N x 124º 49.005W


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## downeast450 (Jan 16, 2008)

I have to agree that a competent skipper can be distracted! No texting!

Down


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## Maine Sail (Jan 6, 2003)

downeast450 said:


> Maine,
> 
> I am amazed at that number of hard groundings / year. I spend much of the sailing season along the Maine coast and have many friends who sail here. I only know of two hard hits around MDI in the past few years. I guess I don't know as many sailors as I thought. My sailing friends are "locals". Is the carnage you mention happening to boats from "away"? There are not that many "hidden" spots if the skipper is competent.
> 
> Down


A lot are from away but a lot are from here too. I know of three boats that hit ledge this season during races while trying to avoid tacking. I suspect the folks up your way might not be telling you of their groundings? I know my two customers were a little bashful. One hit Upper Basket and the other hit Lower Basket ledge.

I am in and out of yards all week so I get to see the boats on the hard with the keel damage. Most are just buttered up, faired and re-launched and some just haul to check then re-launch without repair and hold off until the winter..

That number of course is just a rough guess based on what I see here in Casco Bay and I extrapolated it out to the rest of the coast...

I would guess Casco Bay has at least 75-100 hard groundings. We have approx one or two boats per week on the ledges just off our anchorage, Upper Basket Ledge, Lower Basket Ledge, Sturdivant Ledge, & Lower Clapboard Ledge are some of the more popular ones for donating lead to, and that just what's within eye sight.

Heck even one of our local Schooner captains put his boat on a ledge not once but TWICE!! Oh and the Portland Fire Boat hit ledge too..... So it's not just us "amateurs"... 

Portland Schooner On Rocks








Portland Fire Boat Hits Ledge


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## downeast450 (Jan 16, 2008)

Maine,

A quick look at the charts of Casco Bay and the waters near MDI, suggests there are more opportunities to "donate lead" where you are. We certainly have our share of beautiful Maine granite but our sailing spaces are not as "compromised" by ledges in the high traffic areas. Setting a race course in Western Way or Great Harbor almost never needs to come close to water less than 5 fathoms deep. I will be extra cautious next summer if I make it down the coast that far. Racing is a separate category of judgment calls. Especially if you can afford the risk of repairs for a win.

Down


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## SloopJonB (Jun 6, 2011)

One of the first sayings I learned about boats was "Anyone who says they've never hit bottom is either a liar or has never left the dock."

While it may not be literally true, it's close enough.


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## downeast450 (Jan 16, 2008)

In my 40 years of sailing along the Maine coast and 15 years elsewhere I have certainly "misjudged" the depth more than once. It hasn't happened to me on my Islander, yet! Ha! I have used a cb as a depth sounder! My Marshal Catboat hits a sand bar about once a year but I am aware of the shallows and expect it. Smacking a ledge at speed with a deep fin is something I have managed to avoid. I will keep trying!

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