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Old 11-11-2014, 05:06   #46
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Re: What are the disadvantages of a 6'-7" draft?

Many thanks to all for the replies! It's been very helpful and very interesting.

Duane
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Old 14-11-2014, 12:12   #47
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Re: What are the disadvantages of a 6'-7" draft?

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Originally Posted by carlylelk View Post
We are serious about an Amel Super Maramu, 53' LOA, a 6'-7" draft, 15'-1" beam, and a 65'-3" mast height. We'll be on the east coast, the Bahama's, and then down-island to the Caribbean. I'm more than a little concerned about limitations on anchoring, mooring, and the ability to tour the Bahama's.

We have a long list of good reasons for the boat selection, but the draft worries me.

I plan on getting a planing dinghy so we can anchor at some distance and visit some of the nicer spots in the Bahamas that are too shallow.

Any advice is appreciated.
This question has been considered before. However, I never see anyone mention the idea of "safety factor". Call me overly cautious, but when the going gets shallow, I worry about a slightly erroneous chart or tide prediction, unanticipated large waves, uneven bottom, the uncharted boulder, or discarded engine block, that I could just be unlucky enough to hit.

So, what's your safety factor?
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Old 14-11-2014, 13:00   #48
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Re: What are the disadvantages of a 6'-7" draft?

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This question has been considered before. However, I never see anyone mention the idea of "safety factor". Call me overly cautious, but when the going gets shallow, I worry about a slightly erroneous chart or tide prediction, unanticipated large waves, uneven bottom, the uncharted boulder, or discarded engine block, that I could just be unlucky enough to hit.

So, what's your safety factor?
I think safety is a given in the whole discussion of grounding. Now all those safety issues exist on any draft. The question is how much do they increase with a 6'7" draft. Versus 5'6" just a little. Versus 3' quite a bit. But then you see a lot of shallow draft vessels run aground as their owners sometimes think they're immune.

It reminds me of people who think they can run jets anywhere. We have jet tenders and the draft is around a foot. But that doesn't mean one should run them regularly in 2 feet of water. Those who do have trouble as they pick up all sorts of marine growth and silt and ultimately they get clogged. I've seen jet skis run aground.

Another key to safety is speed in the suspect areas. Obviously a boulder or something like that will cause severe damage, but most of the time we're talking shoals and while they will be embarrassing and inconvenient, going slowly on to one will not generally create a safety issue.
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Old 14-11-2014, 13:39   #49
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Re: What are the disadvantages of a 6'-7" draft?

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Originally Posted by The Smokester View Post
This question has been considered before. However, I never see anyone mention the idea of "safety factor". Call me overly cautious, but when the going gets shallow, I worry about a slightly erroneous chart or tide prediction, unanticipated large waves, uneven bottom, the uncharted boulder, or discarded engine block, that I could just be unlucky enough to hit.

So, what's your safety factor?
This is all part of seamanship: knowing your vessel and adapting your practices to allow for all factors. There is no magic draft number that makes you safe, and a competent skipper will be equally safe with whatever draft he is lumbered with.

If you require a "safety factor" that will keep you from running aground, best stay tied to the dock... assuming that your berth is deep enough!

Jim
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Old 15-11-2014, 13:45   #50
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Re: What are the disadvantages of a 6'-7" draft?

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I think safety is a given in the whole discussion of grounding. Now all those safety issues exist on any draft...
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Originally Posted by Jim Cate View Post
This is all part of seamanship: knowing your vessel and adapting your practices to allow for all factors. There is no magic draft number that makes you safe...

Jim
I agree. I guess I'm still learning and wonder what people's experiences are coming into a bay or lagoon with the chart showing a nice, flat bottom of, say, 10 feet and still running aground (with a 6 foot draft).
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Old 15-11-2014, 13:56   #51
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Re: What are the disadvantages of a 6'-7" draft?

CF Mod Dockhead had a great write up of his trip through the Baltic. Unfortunately part of that trip (as I recall) was hitting an unmarked underwater rock in what should have been a deep enough anchorage. So it's not like it never happens. I try to always leave 2-3 feet underneath as my safety margin, especially since one can't see the bottom in New England.


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Old 15-11-2014, 15:19   #52
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Re: What are the disadvantages of a 6'-7" draft?

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I agree. I guess I'm still learning and wonder what people's experiences are coming into a bay or lagoon with the chart showing a nice, flat bottom of, say, 10 feet and still running aground (with a 6 foot draft).
One must use every source of information, not just the charts. For instance, on the East Coast of the US there are two sources that have alerts published regularly. There is another internet source updated based on boater experience. Then there is local knowledge from those you meet at marinas, from those in the area to which you're headed from passing boats, from tow captains. There is your electronics from depth finders to more advanced some have such as sonar. Certainly not least is visual observation. Notice how waves are breaking, water color and any other signs.

Then there is still risk. Most running aground is operator error but a little of it really isn't, just change in conditions. Either way, it happens and you're just hoping to minimize it. You also want to minimize the damage and severity. When you notice something that doesn't seem right, you slow down and figure it out. You also take conservative routes and measures. I've seen times with 18' channels and a boat would run aground cutting a corner and then complain that it was supposed to be 6' and turned out to be only 4'.
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Old 15-11-2014, 17:55   #53
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Re: What are the disadvantages of a 6'-7" draft?

Originally Posted by carlylelk
Could you give me a few examples of east coast anchorages that would be difficult with deep draft?

Thanks in advance,
Duane



6-4 draft: Ran aground hard just outside the stadium anchorage in Biscayne Bay, had to be towed off. Ran into something in the ICW channel just outside Harbortown Marina entrance Fort Pierce. Ran onto the bottom entering a small bay in the Bahamas just south of Georgetown. managed to get thru and awaited high tide the next day to get out. Was grounded when the tide went out one night on one of the "lake" anchorages along the ICW. Got there just at nightfall and just anchored where convenient...


bumped and plowed here and there all along the ICW from NC on south.
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Old 16-11-2014, 06:46   #54
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Re: What are the disadvantages of a 6'-7" draft?

Quote:
Originally Posted by Jim Cate View Post
This is all part of seamanship: knowing your vessel and adapting your practices to allow for all factors. There is no magic draft number that makes you safe, and a competent skipper will be equally safe with whatever draft he is lumbered with.

If you require a "safety factor" that will keep you from running aground, best stay tied to the dock... assuming that your berth is deep enough!

Jim
I think that by "safety factor" he means how much extra depth do you need beyond the depth of your boat before you feel confident that it's unlikely that you'll touch bottom. That's a personal thing and we all have a number like that in our heads whether we are dock kings/queens or the most intrepid world cruisers. I've learned that number can vary widely, depending on where I am and what boat I'm on.

For example, in Maine where the depth is almost always at least 20' even in harbors, and much deeper virtually everywhere outside of harbors, I start getting uncomfortable when I see anything less than about 10' beneath my keel. But when I had my boat in the Bahamas, I had to become accustomed to and even comfortable with regularly seeing 2 or 3 feet on the depth sounder. In Maine there's so much deep water that there's no need to subject myself to shallow depths and I know that it's almost never soft sand down there, but rather is likely to be a jagged ledge, whereas in the Bahamas, unless I hit coral that can usually be seen, it's usually more forgiving soft sand. Enroute between the two places, off Cape Hatteras, I don't want to see anything less than a couple hundred feet beneath my keel.

Another consideration is the boat I'm on. My previous boat had external lead ballast so I wasn't as concerned with bumping something down there as I am now with my encapsulated iron ballast. So my needed "safety factor" before I feel comfortable has increased by a few feet on this boat with this type ballast.

Also, while coastal cruising near the United States, where, should I need it, a quick tow off or even rescue is likely to be available, while I certainly hope to never need rescuing or even towing, I'm less concerned about shallow depths than I would be approaching a remote coral reef thousands of miles from any source of assistance.

I think it's pretty clear that we all have a 'safety factor" in our mind that's more than the draft of our boat and that number can vary, depending on many factors, from our experience level, to our location, to the type boat we're sailing and probably to many other factors I haven't even thought of. It's very normal and there's certainly nothing wrong with it.
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Old 16-11-2014, 10:50   #55
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Re: What are the disadvantages of a 6'-7" draft?

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Originally Posted by brownoarsman View Post
CF Mod Dockhead had a great write up of his trip through the Baltic. Unfortunately part of that trip (as I recall) was hitting an unmarked underwater rock in what should have been a deep enough...
Thanks. I wonder, if this happens, how one can learn to do things differently. Of course, life happens regardless. I guess this is reinforcing evidence that you can never let your guard down, particularly in a strange place.

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One must use every source of information, not just the charts. For instance, on the East Coast of the US there are two sources that have alerts published regularly. There is another internet source updated based on boater experience. Then there is local knowledge from those you meet at marinas, from those in the area to which you're headed from passing boats, from tow captains. There is your electronics from depth finders to more advanced some have such as sonar. Certainly not least is visual observation. Notice how waves are breaking, water color and any other signs...
Good advice. Does anyone have one of the forward looking sonars? Do they give enough early warning? Are they useful?

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Originally Posted by Cheechako View Post
...bumped and plowed here and there all along the ICW from NC on south.
Yikes!

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Originally Posted by jtsailjt View Post
I think that by "safety factor" he means how much extra depth do you need beyond the depth of your boat before you feel confident that it's unlikely that you'll touch bottom...
Yes! Thank you for the insightful and useful post. Much to think about.
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Old 16-11-2014, 11:51   #56
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Re: What are the disadvantages of a 6'-7" draft?

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Good advice. Does anyone have one of the forward looking sonars? Do they give enough early warning? Are they useful?
We have them. Don't think of them as something that will help you while under full speed and doing normal cruising. Think of them as a special need application. Extremely helpful when in an area you have questions about. If you want to see how far out the shoaling is they can be very useful. I recall once there was a charted obstruction near a marina but the marina had just rearranged their docks. We found it easily with sonar. We've been in areas new to us in the PNW and now down to the Bay area. It's a very useful extra tool. A couple of times it's given us a very different picture than the charts indicated, primarily when approaching a marina.

Now, range is advertised at 1/4-1/2 miles and they will operate up to 20 knots or so. But at 20 knots you cover the distance in a minute. So while on an open ocean they might see a container, the likelihood of you seeing it in time to avoid it is somewhat slim. At a slower speed it's possible but most people don't keep their eyes on radar or charts or sonar every minute.
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Old 16-11-2014, 11:53   #57
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Re: What are the disadvantages of a 6'-7" draft?

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We have them. Don't think of them as something that will help you while under full speed and doing normal cruising. Think of them as a special need application. Extremely helpful when in an area you have questions about. If you want to see how far out the shoaling is they can be very useful. I recall once there was a charted obstruction near a marina but the marina had just rearranged their docks. We found it easily with sonar. We've been in areas new to us in the PNW and now down to the Bay area. It's a very useful extra tool. A couple of times it's given us a very different picture than the charts indicated, primarily when approaching a marina.

Now, range is advertised at 1/4-1/2 miles and they will operate up to 20 knots or so. But at 20 knots you cover the distance in a minute. So while on an open ocean they might see a container, the likelihood of you seeing it in time to avoid it is somewhat slim. At a slower speed it's possible but most people don't keep their eyes on radar or charts or sonar every minute.
Can you set alarms?
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Old 16-11-2014, 12:49   #58
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Re: What are the disadvantages of a 6'-7" draft?

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Can you set alarms?
Yes, you can, at least on some of them.

The science is far beyond me but they do have to make many scans to provide one picture so there is a second or longer delay. The other thing is that water depth influences how far forward they can detect. They are only able to measure water depth between 8 and a maximum of about 12 times as far forward as the water is deep. So if you're looking for water depth and it's 6', then they'll only be able to measure that accurately from 50-60' or so. Also I'll point out that they're designed to operate under moderate sea conditions. Their ability under extreme conditions is limited and determined somewhat by mounting and how far under the water they are. The further the better.

Sonar is being used for many things from fishermen trying to follow structure to large commercial vessels using it for security while docked to detect divers.

While Sonar is not new it's still very early in it's development cycle I think, for marine operations. I've only been exposed to it a few months. I would by no means consider myself expert in using it. I would not at this point put my boat completely in it's trust. However, I do think it's another tool. Some may consider it an expensive toy, but radar on boats was once considered that. In fact, when we had radar on the lake we lived on, people laughed and made fun of us. They were right 99.9% of the time. We were just playing with it those times. But I remember a couple of times we were very happy to have it. My father didn't give in to depth finders for fishing for years.

Now, we're gadget people so we're very into new technology.
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Old 16-11-2014, 14:42   #59
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Re: What are the disadvantages of a 6'-7" draft?

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Yes, you can, at least on some of them.

The science is far beyond me but they do have to make many scans to provide one picture so there is a second or longer delay. The other thing is that water depth influences how far forward they can detect. They are only able to measure water depth between 8 and a maximum of about 12 times as far forward as the water is deep. So if you're looking for water depth and it's 6', then they'll only be able to measure that accurately from 50-60' or so. Also I'll point out that they're designed to operate under moderate sea conditions. Their ability under extreme conditions is limited and determined somewhat by mounting and how far under the water they are. The further the better.

Sonar is being used for many things from fishermen trying to follow structure to large commercial vessels using it for security while docked to detect divers.

While Sonar is not new it's still very early in it's development cycle I think, for marine operations. I've only been exposed to it a few months. I would by no means consider myself expert in using it. I would not at this point put my boat completely in it's trust. However, I do think it's another tool. Some may consider it an expensive toy, but radar on boats was once considered that. In fact, when we had radar on the lake we lived on, people laughed and made fun of us. They were right 99.9% of the time. We were just playing with it those times. But I remember a couple of times we were very happy to have it. My father didn't give in to depth finders for fishing for years.

Now, we're gadget people so we're very into new technology.
Very interesting descriptions of your (early) impressions. I've read about cruisers in the S. Pacific using it quite effectively to navigate through narrow entrances to coral atolls, etc. Like everything else, I imagine the technology will only improve over time. I am definitely interested in following any developments.
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Old 16-11-2014, 14:56   #60
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Re: What are the disadvantages of a 6'-7" draft?

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Very interesting descriptions of your (early) impressions. I've read about cruisers in the S. Pacific using it quite effectively to navigate through narrow entrances to coral atolls, etc. Like everything else, I imagine the technology will only improve over time. I am definitely interested in following any developments.
Definitely a good tool for reefs. We just haven't made it to any yet. But we've used it on some inlets with relatively narrow channels. I can see using it in the Bahamas and throughout the Caribbean.
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