leaving marina berth - help please

[Poignard]

Another option is to copy certain long-keeled MAB owners around here - just go for it, see what happens, then make out that's how you planned it.

That's the way I do it.

Sometimes I sail proudly away with spectators applauding my superior boat-handling skills.

Other times I slink off in disgrace, with people screaming abuse and threatening violence and legal action.

 

[Dockhead]

Bit sad really that if google has'nt heard of something then it does'nt exist.

It's quite simply a term used that describes exploiting the tendency of a boat's stern to seek the wind by reversing into the wind. It implies movement by the boat. Weathercocking implies a static boat where the bow is blown off.

Hope that helps.


I'm astounded that so many have'nt heard of the term.

It's not "so many" but not one single person, who has heard of this term, so far on this forum. Must be something local. Sounds a bit like an old-fashioned naval sexual practice, I must say.

In any case, it's nothing else but weather-cocking, something familiar to every sailor. It's an effect created by the same principle that creates weather (or lee) helm. Centre of aerodynamic pressure is offset forward compared to the axis of your boat's keel, so the wind will exert a force tending to make your boat yaw stern into the wind. This force will be greatest when the wind is on the beam. It will be most noticeable on a lightweight fin keeled boat with a flattish bottom which has the least resistance to yawing. It is related to relative wind (obviously) so you can increase the effect by backing into the wind, if you want to use it to help turn the boat.

The same principle can make it hard to put your boat's head into the wind (or turn through the wind) in forward if you don't have enough way on to have enough rudder authority to overcome the weather-cocking force. You will be fighting the wind to gain way and get rudder authority, and all the while the bow is blowing off. If you are backing off and turning, however, this effect will be much less pronounced, because the wind is helping you gain way and thus rudder authority, instead of fighting you. And the angular force exerted on the boat will diminish as the boat's head approaches the direction of the wind. That's why it's much easier to snap around through even a very strong wind while backing down, compared to trying to do the same manuever in ahead.

We spent a lot of time talking about this, but despite the confusing terminology I think these basic principles are familiar to nearly all sailors with more than one season under their belts.

 

[jimi]

It's not "so many" but not one single person, who has heard of this term, so far on this forum. Must be something local. Sounds a bit like an old-fashioned naval sexual practice, I must say.

In any case, it's nothing else but weather-cocking, something familiar to every sailor. It's an effect created by the same principle that creates weather (or lee) helm. Centre of aerodynamic pressure is offset forward compared to the axis of your boat's keel, so the wind will exert a force tending to make your boat yaw stern into the wind. This force will be greatest when the wind is on the beam. It will be most noticeable on a lightweight fin keeled boat with a flattish bottom which has the least resistance to yawing. It is related to relative wind (obviously) so you can increase the effect by backing into the wind, if you want to use it to help turn the boat.

The same principle can make it hard to put your boat's head into the wind (or turn through the wind) in forward if you don't have enough way on to have enough rudder authority to overcome the weather-cocking force. You will be fighting the wind to gain way and get rudder authority, and all the while the bow is blowing off. If you are backing off and turning, however, this effect will be much less pronounced, because the wind is helping you gain way and thus rudder authority, instead of fighting you. And the angular force exerted on the boat will diminish as the boat's head approaches the direction of the wind. That's why it's much easier to snap around through even a very strong wind while backing down, compared to trying to do the same manuever in ahead.

We spent a lot of time talking about this, but despite the confusing terminology I think these basic principles are familiar to nearly all sailors with more than one season under their belts.

Look Dockhead, everyone that knows about manouvring boats has told you your advice on this thread about getting the head of the boat through the wind is complete and utter bollox.

You're obviously trying to retrieve some sense of dignity by attempting to get the last word in, so go for it.

I've got better things to do with my time than argue about semantics with you.

 

[flaming]

Jimi, your boat handling advice is spot on, agree 100%. Attempts to get the bow through the wind in this situation are best done with your check book in your throttle hand.....

Never heard the term "Stern Boring" before though. Mind you, I'm a couple of decades under the average age hereabouts....

 

[Phoenix of Hamble]

I'd go as far to say, that in the Bavaria the OP mentioned, with 20kts across the beam in a marina aisle, it would be nigh on impossible, let alone difficult to get the bow through the wind.... I watch boats make this exact basic mistake nearly every weekend the wind is above 10kts.

 

[Phoenix of Hamble]

As an aside.... I did once from my home berth when it was quite windy, just let the boat blow down gently onto the end lateral pontoon deep in the aisle (there was space due to a boat being away and i'm only 1 finger from the end so not really time for the bow to blow down too far), and then spring aggresively off from there.... it wasn't really 100% neccessary, but was good practice for the crew.

It would be another option, albeit a rather convoluted one.

 

[Dockhead]

Look Dockhead, everyone that knows about manouvring boats has told you your advice on this thread about getting the head of the boat through the wind is complete and utter bollox.

You're obviously trying to retrieve some sense of dignity by attempting to get the last word in, so go for it.

I've got better things to do with my time than argue about semantics with you.

I was not proposing an argument over semantics or anything else, nor do I seek dignity on internet forums. I am a few decades to old to confuse the virtual world with the real one, I guess. I was commenting on some odd terminology, for what it is worth to anyone.

But you can easily get just about any boat's head through the wind from stopped by backing down and turning instead of going ahead. This is simply a fact. Try it some time.

 

[flaming]

But you can easily get just about any boat's head through the wind from stopped by backing down and turning instead of going ahead. This is simply a fact. Try it some time.

Yes, eventually, but in the conditions we're talking about not before you've run out of room.

In fact, I'd be suprised if you got the boat back to it's original angle before you hit the pontoons opposite. And 20kts is not exactly all that extreme. I once had a similar situation when I decided to bug out in 40kts, I doubt I'd have got the bow through the wind before I was doing 6 knots in astern, which is a bad idea any way you cut it.

But anyway, why would you want to do that? All that does is fight the elements. Much, MUCH better to get the elements working for you.

 

[Dockhead]

Yes, eventually, but in the conditions we're talking about not before you've run out of room.

In fact, I'd be suprised if you got the boat back to it's original angle before you hit the pontoons opposite. And 20kts is not exactly all that extreme. I once had a similar situation when I decided to bug out in 40kts, I doubt I'd have got the bow through the wind before I was doing 6 knots in astern, which is a bad idea any way you cut it.

But anyway, why would you want to do that? All that does is fight the elements. Much, MUCH better to get the elements working for you.

Yes, maybe, I take that on board. It is very surprising to me to hear that you can’t get your boat’s head through the wind in astern until 6 knots. That doesn’t correspond at all to my experience. But I have never owned a lightweight fin-keeled boat, so your experience is probably more relevant to the OP. My boat’s head will snap right through any wind in astern, but then I have a lot less weathercocking than the Bav in the OP – my boat’s cutter-rigged with the mast further aft than a sloop, so the centre of pressure is closer to the keel. Plus she weighs 24 tonnes and has 2.4 meter draught so she’s not blown around nearly as much by the wind in any case. I can get her head through the wind in ahead, too (at least, anything under 40 knots), just not as snappy as in astern.

My last boat (for 20 years prior) was a heavy 37' longish-keeled cruiser which simply wouldn't back down in any case, so none of these maneuvers were relevant. In that boat in the given problem I would have simply had to manhandle the boat around with warps into the aisle. Or more likely, go back to bed and wait for the wind to pipe down.

It's an interesting problem and has been an interesting discussion, despite some of the testosterone-infused silliness. Certainly it's inspired me to try out all of these manuevers again to be sure that reality indeed corresponds to the way I imagine them.

 

[dt4134]

But you can easily get just about any boat's head through the wind from stopped by backing down and turning instead of going ahead. This is simply a fact. Try it some time.

You'd have to use a lot of power in those conditions to try to straighten the boat out going astern with that wind on the bow, and you don't have the room for that.

You could probably get the bow through the wind by going full ahead into a hard over rudder, although, subject to my remembering the Bav 36 correctly, it would be hard as the boat would shoot forward before turning. It would be easier on some of the other Bavs & other AWBs.

But the whole point is why? You can easily go out stern to wind with a lot less effort and find the sea room to turn.

I'm with the majority here. In boat handling it is easiest to do what the boat wants to do and you should only be fighting the boat when you have to.

 

[flaming]

Yes, maybe, I take that on board. It is very surprising to me to hear that you can’t get your boat’s head through the wind in astern until 6 knots.

In 40 knots of breeze.....

I doubt I'll be alone in doubting that you can get a 24 tonne boat to get the bow through the wind in 40kts, let alone whilst travelling slower than 6 knots....

 

[jimi]

I rather suspect that a film of getting a 24T boat to turn round in the narrow confines of a marina aisle in 40Knots of wind would be an instant You Tube hit (even if he had a bow thruster)!

 

[Dockhead]

In 40 knots of breeze.....

I doubt I'll be alone in doubting that you can get a 24 tonne boat to get the bow through the wind in 40kts, let alone whilst travelling slower than 6 knots....

Well, I can only theorize (perhaps wrongly) about Bavs, but about my boat I know for sure. That is proven by experience. Last October and November in the Solent we had 40 knots almost every weekend as you might remember, and I was out every weekend.

My boat (a Moody 54) has a very large, partially balanced skeg-hung rudder, and has little windage for her displacement. The rudder gives very strong authority from about 1 knot. I can easily spin her in her own length with a little burst ahead and astern. In 40 knots I can point her in any direction I like from a standing start (sea state allowing, of course). She just comes around more slowly in ahead than astern because of the mild degree of weathercocking she is subject to (she turns ok in ahead too, possibly, because, unlike our Bav, she has shaft drive, and the 30 inch propeller washes right onto the rudder in ahead) . I've got a 10 horsepower bow thruster just in case, but never needed that in this kind of maneuver.

And it's a damned good thing, too, because otherwise I would just not have the nerve to maneuver her in the tight marinas around here. A turn in a marina aisle which is comfortable for a 40 foot boat can become disastrously tight when you have 60 feet from bow roller to davits.

The heavy displacement is a big advantage maneuvering in strong winds. The disadvantage of this is inertia, which means it takes a long time to stop. That means you have to be a lot more analytical with your maneuvers, so that you are able to give control input to the engine and gearbox quite a long time before you expect a reponse.

In my old boat (10 tonnes, 37 feet, low freeboard, barn-door rudder) after 20 years I maneuvred pretty much like one of the other posters here -- squirt and go. Plenty of power and steer. As long as I could see a way through the maneuver without backing (with the long keel, she backed in circles, only occasionally useful). I absolutely cannot do that with the present boat -- every maneuver has to be analyzed and planned ahead, so I'm in the process of rethinking every thing I know about close-quarters maneuvring. That's why these threads have been so interesting for me.

 

[Ubergeekian]

If that was my boat (long keel, puny engine, high bows) I'd walk her back along the finger as far as I could, then give her a good shove and tie the bow to the end of the finger, let her align with the wind, pull in a spring from the middle of the starboard side until she was across the end of the finger, push off, jump in and only then try to use the engine. 'Course she's only 3 tons which makes warping around a lot easier than on heavier things.

 

[westernman]

If that was my boat (long keel, puny engine, high bows) I'd walk her back along the finger as far as I could, then give her a good shove and tie the bow to the end of the finger, let her align with the wind, pull in a spring from the middle of the starboard side until she was across the end of the finger, push off, jump in and only then try to use the engine. 'Course she's only 3 tons which makes warping around a lot easier than on heavier things.

You could probably manage without the middle spring - you can use the propwash in forward gear over the rudder with about half the engine power (i.e. not actually enough to move her forward), to align the boat how you want to.

I did it like that when leaving a commercial dock in a F8 cross wind (fortunately the dock on the upwind side of the boat) and it was all very straightforward. If the dock had been downwind, it would have been almost impossible to get off as we were laying alongside.

 

[Dockhead]

I rather suspect that a film of getting a 24T boat to turn round in the narrow confines of a marina aisle in 40Knots of wind would be an instant You Tube hit (even if he had a bow thruster)!

I'm fortunate that my own marina's aisles are not all that narrow. But my berth requires a fairly tight (for my length) 180 degree turn to get into. I've made this turn (which by definition requires turning through the wind) at least 50 times this year, often in 30 knots or more. I keep the bow thruster warmed up and ready but it's become fairly routine.

Coming out of my berth (I berth port side to the finger) is also pretty tricky because the berth next to mine is offset behind me (the pontoon dog-legs). So I have to reverse quite a distance before I initiate my turn, then I have to get the boat turned 90 degrees with less than a boat length left before the other side of the aisle. This is a tricky manuever because my prop kicks mildly to port and with 16 feet of beam I have only two of feet of space to the boat to starboard of me. Here I just couldn't do it without the thruster (at least I don't know any way to do it). I thrust first to port to angle the boat away from the finger, then slow astern neutral helm to get the topsides clear of the finger, then let the prop kick straighten the boat up. Within a third of a boat length I've got rudder authority and am backing straight (so different from my old long-keel boat) out of the slip.

Once the stern of my boat is clear of the boat to port of me, I initiate a sharp turn to port. The bows have to come through the prevailing (west or southwest) wind in order to make this turn. But by the time I've reversed past the boat to port of mine I have maybe two knots of way on, and putting the big rudder over to port snaps the boat right around. Usually I don't need the thruster for this, although being a coward I will use it in anything over 30 knots just to be damn sure there is no delay in getting the bows through the wind. After spinning the boat around bows through the wind, I proceed out of the aisle in ahead.

My boat kicks mildly to port, so I will usually give it a couple of bursts in astern during this 90 degree turn to help get the bows through the wind.

Done it at least 50 times this year in winds sometimes up to 40 or maybe a little more (I sailed all winter). Never scratched anybody, although I've had two boats, annoyingly, crash into me during the year.

These maneuvers would be completely impossible in the Bav you describe, if she behaves the way you describe, but I allow as that may well be the case.

 

[Ubergeekian]

You could probably manage without the middle spring - you can use the propwash in forward gear over the rudder with about half the engine power (i.e. not actually enough to move her forward), to align the boat how you want to.

True. On the other hand, my usual crew member is 4 years old, so I generally have to do things a wee bit more myself. I prefer to hoik the boat round to where I want her, get on and go.

Anyway, what do you mean "half power"? It's a Yanmar 1GM10 - it only has half power when it's at full power.

 

[westernman]

Anyway, what do you mean "half power"? It's a Yanmar 1GM10 - it only has half power when it's at full power.

Half power (in the forward direction) is what you use to not go backwards too fast when pointing forwards into the wind.

Full power is what you use to creep forwards against the wind.

I know the feeling:- we had a long motor against an F9 a few weeks back, making at times less than 1.5 knots at full power. F9 is too much wind to make way against under sail as well (although we can stay very confortably stay hove to).

Mine is a Yanmar with 89 horses. But with 66ft from bow sprit to stern and several miles of rigging, the windage is huge.

 

[Ubergeekian]

Half power (in the forward direction) is what you use to not go backwards too fast when pointing forwards into the wind.

Full power is what you use to creep forwards against the wind.

I had occasion to observe all the effects in a bit of a blow on the Clyde earlier in the summer. With 20 kt wind she'll just keep steerage way. At 30 kt she will go straight into the wind, but the slightest deviation blows the bows off and the only hope is to do a 360 and catch her at the head-into-wind position again. At 40 kt she just blows downwind any damn way she wants to.

 

[flaming]

Last October and November in the Solent we had 40 knots almost every weekend as you might remember, and I was out every weekend.

In nit-picking mode, I would question this. I was out every weekend of October and November (as I will be this year) for the Hamble Winter series. As far as I recall it was only over 30kts consistently twice during the Winter series last year. One they cancelled, and one we raced, max wind speed (in the central solent) of 37kts. If anyone has a bunch of time on their hands, the records will be available on bramblemet.

Regardless, it's quite clear that a Moody 54 (very, very nice boat btw) is a lot more stable under power than an AWB. That 30" prop, and 24 tonnes of weight certainly isn't going to add up to a boat that's easily blown off course. However, you still seem to be saying that it is easier to get the bow through the wind whilst going astern than it is going ahead. That would make the Moody 54 unique I believe!