Navigation help

Ray T · Apr 10, 2012

I would have done the same thing. If you were wrong we both would have been. A lot of these soundings on charts haven't been updated in years and the rivers and creeks have silted in. In unfamilier waters that show minimal depth for your boat unless you have a lead line to throw out in front of your boat just take it slow. I guess most of us have run aground at one time or another.

JVB · Apr 10, 2012

I don't see what the problem is. Seems like you found exactly what the chart shows, i.e. water too shallow for your boat.

GeorgiaBII · Apr 10, 2012

I'm not sure I'd go into an area that is listed as only having 4" of water below my keel... But I have almost NO experience sailing.

Caboteur · Apr 10, 2012

Hi,
You did nothing wrong: the chart shows 5ft at mean low water... if the chart doesn't give you a very wide margin of error, go slow you are very close to bottom. If there is any irregularity in the bottom configuration, you touch. If you are going slow enough that's all that happens... if the tide is going out you might have to wait six hours, if it is still coming in you're off in a few minutes.
There are several ways to look at this: you may wish to limit your forays to 10ft depths or you may risk touching in the right circumstances... I like to explore a lot and I touch more often than most! This winter I had my rudder repaired and will be fairing and refinishing my keel and will continue going to interesting places that are a bit shallow.

Tom L · Apr 10, 2012

Hi Warren, I take it you were returning to the marina? I am not sure, I have not grounded at that point but my draft is only 4.5 ft. Last time I was out I grounded further out close to the day markers. I guess you should have gone straight at the end or turned a little to the starboard instead of turning to port. Are there any small white markers out yet close to the marina?

Well, good to hear that your boat is in. Did you see if they put mine in yet?
Regards,
Tom

Dave Groshong · Apr 10, 2012

Charts are fairly accurate, but are just guidelines really, shifting sand and silting can easily sway the depth by a foot or two, that's why local knowledge is so highly valued. You did nothing wrong other than taking it too close to the edge, the "prudent mariner" always errors on the side of safety. I agree that you may want to limit your grounds to 8-10ft.

CalebD · Apr 10, 2012

If your marina is up in there you are just going to have to get really good at finding your way in and out, noting the relative tides and wind driven tides will be important.
You did nothing wrong but you did find one place you can hit bottom, no harm, no foul. It will be good practice for you to figure out all the ways of getting your boat off the bottom: reversing off, kedging with an anchor, heeling the boat and sometimes even jumping in to push her off all work.

I doubt the satellite images of the harbor would help a lot figuring out what the current underwater topography looks like but it might be worth a look: http://maps.google.com/maps?hl=en&s...esult&ct=title&resnum=2&sqi=2&ved=0CDUQ8gEwAQ

DeniseO30 · Apr 10, 2012

you went in on a rising tide, that IS a GOOD thing! My boat needs 5ft so I'd go very very slow

Benny17441 · Apr 10, 2012

You ask what I would have done. I would have realized that the marging of safety between what the boat draws and the charted depth at mean low water was to narrow. If I had to go in there I would try at high tide slowly feeling my way in and watching the depth sounder to record the shallow spots to be able to plan my way out. Here in Florida we do a lot of skinny water navigation and recognizing that the soundings on the charts may be old we like to give ourselves a better margin than 6". I did not see a marina in that chart but if there was one I would be on the VHF procuring local knowledge. Having a chart plotter that creates a record of how you went in can be of great help in getting out. It is a fact of life that the longer the keel the less number of locations are reachable. If you have the time and like to gunkhole you can chart the waters yourself and map out the bottom contours. Other than being a little ambitious you did fine.

Stu Jackson · Apr 10, 2012

I agree. There do seem to be docks just to the north and east of the end of the red line.

dparilla · Apr 10, 2012

I deal with a low tide issue almost daily now. With the lack of rain on the east coast lately and no snow melt to speak of, the channel to my marina is 2 feet lower than charted depth. I draw 4'6" and at low tide, I "kick up the silt" all the way in. Such is the joy of river sailing, just go slowly, and have a kedge plan ready for if and when you get stuck. Small children (heck even adults) on a sling off the boom works really well and the ballast...I mean rider... has fun too. I keep my guard up until the fatho reads 8 feet, then I know I am clear. If it drops under 8, I start to watch. At 4 feet I know I have 2 under the keel, then at 3, we go to bare steerage. 2 feet and we are on bottom.

Anchor Down · Apr 10, 2012

This isn't navigation: it's piloting.

Gudenuph · Apr 11, 2012

twistedline said:
Hi, I'm just after some advice about entering a river for the first time and what other people do / check. I'm was an avid dingy sailor but now have Hunter 25.5 and draw 4'6" so plenty more to worry about.

Here's a snippet of the chart: http://i.imgur.com/ecqZU.jpg which shows the river I entered. The red line (I did this in paint, so its a little wobbly) roughly shows my route. Low tide was at around 2:30pm we entered at around 4:30pm.

We touched the bottom where the red line ends, depth finder was showing 5ft most of the way, we got stuck the moment it went to 4ft. I got out easy enough but I am interested in what I did wrong and how other people would enter this river without having been there before.

Thanks,

Warren.

Just two thoughts: 1) When approaching a shallow narrows on a making tide and which opens into a larger area, watch for a faster current which may take you faster than you wish. In this case if you do ground the current will pin you to the bottom and probably swing you beam on to the current and cause considerable heeling. (Been there, done that) 2) You can sound the bottom well ahead of the boat with a fishing rod with spin reel, by attaching a small weight at the end of the line and a small float up the line at your danger depth. Just cast to the point of interest and if the float submerges you are ok. This works for checking out the anchorage around your boat also, retrieve the line slowly after each cast with pauses to see if the float will show thus indicating a shoal.

FWIW, Geohan

DeniseO30 · Apr 11, 2012

All this has me a wondering are there ANY rocks in the Chesapeake?

AirborneSF · Apr 12, 2012

I'm guessing the only 'rocks' in the bay are fish type.

capta · May 21, 2012

I really don't want to quibble, but the chart says "creek" not river. Rivers generally have enough current to make the outside of a bend the deepest water. Creeks generally don't have enough current to make any channel consistently.
Too many sailors forget that most navigation charts are made for commercial shipping, not pleasure vessels, therefor any water not navigable for commercial traffic is suspect.
Since you must get in and out frequently as this is your marina(?) take your hand held GPS (or borrow one) in your dinghy and find the deepest water (w/ a 4 foot draft, any 6 foot stick or pole would do) by sounding the area. You may be surprised and there is actually a deeper passage not shown on the chart.
I've done many rivers including the Amazon and Orinoco without accurate charts. The trick is to watch the water flow on the surface and stay as far outside on the bends as you can, reasonably, and you should be alright.
Good luck, and if you do come up with a useful full time channel, you might post your info somewhere around your marina for others.

Navigation help

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