Going aground...better astern?

[Iain C]

My boat is normally kept on a mudberth (Quay Lane, Gosport) which has a very tricky entrance, a bit of a channel dredged out of the mudflats which are well and truly dry at low tide. The last time we were out in October, it all went a bit pear shaped as when we tried to get back in on a high tide (which was a neap) we got a bit, erm, stuck! The situation was saved by two chunky mates on the end of the boom, much engine revving and tiller waggling, and we were able to reduce our 4'2" draught enough to get unstuck and leave the boat on a swiging mooring instead. (Still shudder how we managed to make it out the previous morning at 0330 unaware of the issues without getting hidoeusly stuck but that's another story!

Basically, it's very tight getting in and out, and our "suck it see" approach told us that we can't get in on a neap tide, especially if there's high barometric pressure holding the water back a bit...it's that close.

We're off sailing this weekend, and whilst I'm fairly confident that we'll get out OK in the small hours of Sat am, when we come back on Sunday PM, we're coming off springs and things might get iffy again (bit more water this time and lower pressure should help though).

So, my plan is to go up the channel astern, just in case. Theory being...

(boat is a fin keel Sabre by the way, skeg rudder)

1 If we do go aground, it will be faster and more obvious. The back of the keel will dig in quite quickly and she'll stop faster, last time it was much harder to tell we were touching bottom until we were well and truly on it (bottom is nice soft mud remember). If we touch this time, give up immeadiatly.

2 It will be easier to reduce draft by sending everyone forward and unsticking the thinner trailing edge of the keel

3 The boat will presumably produce more thrust in forward gear instead of astern

4 Nearly all of that thrust will be forward thrust, not propwalk

5 All that thrust will be going over the rudder, givng better propwash over the rudder and more scope for wriggling free, or even blowing the mud out the way!

6 Assuming the wind's in a useful direction, easier to just stick some rag up in the event of engine failure, also can use sailpower to heel the boat and reduce draft

7 Most of all the boat is facing in the right direction to get off, so it's not a case of having to get free and then turn, which is more tricky to do without grounding again

8 Could row out the main anchor as a kedge

She obviously does not handle that well astern, but as soon as you have a bit of way on she's OK. Just wondering if anyone else uses a gentle stern first approach if the bottom is soft and theres a high chance of hitting it, or am I comitting a cardinal sin?

Thanks!

 

[Mandarin331]

One concern I would have is if the rudder touched first as this would either damage it or damage the helmsman/woman by slamming the tiller across, but I assume that the keel must be about 12" deeper than the rudder.

My other would be speed, we also have a Sabre (twin keel) and steering astern calls for a certain speed, which means hitting things hard when you do. Ahead we can go much slower with more control and so far have not had any problem with the engine (18 hp) pulling us off astern (touch wood).

I would just take it very easy forward and watch the depth sounder.

 

[bob26]

What about a very slow forward approach with a crewman sounding at the front with a pole marked with your draught?

 

[richardabeattie]

Ingenious solution if you can steer that well in reverse but I can't help feeling that your longer term solution involves moving to a deeper water mooring or switching like me o a bilge keel Sabre! Good luck! Tell us whether it works.

 

[TradewindSailor]

I don't know the Sabre, but I a little concerned that you might damage the keel. As you say it is a lot more slender than the leading edge.

As others have said, I would suggest that you just go forward slowly. Your echo sounder should give you warning enough ..... I used to feel my way into shallow anchorages, slowing down as the depth got shallower.

Another thought: If you go in astern and touch the mud, putting the engine into forward would tend to suck the water out from under the hull and set her harder into the mud. If you go in forward, the thrust astern would send more water under the hull, tending to raise her. Also you prop and intakes would be safer in the deeper water.

 

[Stu Jackson]

If you have wind abeam your bow will blow off, almost regardless of how fast you're moving backwards.

 

[JohnTH]

Well Ian C if you can go astern with the amount of confidence you have in your trusty craft, it must be worth having a go.

Please, come back on and let me / us know how it all worked.

Good luck.

73s de

Johnth

 

[Deleted member 36384]

I am with Tradewindsailor on this. Going forward has advantages as you can normally maintain steerage at a much slower speed than going in reverse. The previous poster that states about sounding ahead from the bow is a very good idea. If you have crew use a lead line or something else to prod the mud with. It only has to be long enough to reach down to the bottom of the keel. A long cane with a flat bottom and a marker to indicate the depth below water line that your keel is. Then just prod your way up, with the flat bottom hopefully indicating the top of the watery ooze more accurately than your depth sounder. Just an idea.

If you are going slow in ahead and the soundings drop to the point where you are likely to be dragging through the top layer of mud then you should be able to stop before you get wedged in. The reverse thrust of the prop may assist in jetting away the top mud.

There is an added advantage that grounding bow first is likely to keep your propellor and rudder in deeper water allowing you to get weight right aft and reverse off if its a gentle grounding. This may be all that is needed before you start hanging out on booms.

The other advantage of slow approach is that the boat will not squat down in the water.

However, give it a go in reverse and see what happens it may be a good way in your situation. If single handed you may be able to still use the cane idea over the quarter.

All the best.