This is a hairy manoeuvre the basic seamanship schools usually avoid, but I'm describing a real live experience that we repeated daily throughout a whole Cowes Week Regatta in the 1970s.
First, let's make it clear that the boat we are talking about was a racing sailing boat 34 feet long, whose auxiliary motor drove a folding propeller. Now let's look at the potential causes of problems.
* * * *
All single screw boats suffer 'prop walk' - going ahead, they turn tighter one way than the other, and going astern the stern is kicked to one side. Normally, you do your best to take advantage of this when planning an approach to a berth.
When you switch from 'ahead' to 'astern', the boat takes some time to stop. The rudder has no effect unless the boat is actually going backwards through the water, and even then it has far less effect than when going ahead because it isn't in the fast-moving slipstream of the prop.
When switching from ahead to astern, folding props sometimes fold flat. When you go ahead, the natural screw action assists centrifugal force in opening both blades again smoothly, but occasionally only one blade will open when you go astern, causing severe vibration and possible damage to the bearing seal. The only option is to return to neutral and try again. Not a joke if you are heading for the end of the dock at the time, with a two or three knot tide helping you.
Our berth was a small pontoon with a gangway from the mid-point to the shore. On the shore side, there were two berths upstream and two downstream of the gangway. We had an upstream one, next to the gangway.
Shallow water began less than half a boat length in from the pontoon, so there was no room to approach the berth from the shore side and turn back out towards it.
We were all racing, so sometimes the berth further from the gangway was already occupied by the time we arrived.
The classic approach to this problem is to face up-tide, get into line and slow right down until the tide walks you very slowly backwards into your berth - with or without the other boat in place, a crew member hops on to the pontoon and warps you in.
Because the shallow, muddy shore was so close, this was risky. Also, on several days there was an erratic, gusty wind.
The technique we ended up using wasn't very kind to the pontoon's moorings, but it worked - just. We went in head first down tide and used a spring to help stop the boat (and once, when the prop didn't open, as the only means of stopping).
A trusted and nimble crew member (sometimes me, but we took turns because it was so scary) took the stern line and a spring, tied to the mast and led through the jib fairlead block (slid up to its foremost position for the occasion). He stood outside the lifelines ahead of the shrouds, and jumped onto the pontoon as early as he could, slipped the spring round the most uptide mooring cleat he could reach and surged the line out, braking the boat's movement as quickly as possible, then tied off the spring and pulled in the stern line.
First, let's make it clear that the boat we are talking about was a racing sailing boat 34 feet long, whose auxiliary motor drove a folding propeller. Now let's look at the potential causes of problems.
* * * *
All single screw boats suffer 'prop walk' - going ahead, they turn tighter one way than the other, and going astern the stern is kicked to one side. Normally, you do your best to take advantage of this when planning an approach to a berth.
When you switch from 'ahead' to 'astern', the boat takes some time to stop. The rudder has no effect unless the boat is actually going backwards through the water, and even then it has far less effect than when going ahead because it isn't in the fast-moving slipstream of the prop.
When switching from ahead to astern, folding props sometimes fold flat. When you go ahead, the natural screw action assists centrifugal force in opening both blades again smoothly, but occasionally only one blade will open when you go astern, causing severe vibration and possible damage to the bearing seal. The only option is to return to neutral and try again. Not a joke if you are heading for the end of the dock at the time, with a two or three knot tide helping you.
Our berth was a small pontoon with a gangway from the mid-point to the shore. On the shore side, there were two berths upstream and two downstream of the gangway. We had an upstream one, next to the gangway.
Shallow water began less than half a boat length in from the pontoon, so there was no room to approach the berth from the shore side and turn back out towards it.
We were all racing, so sometimes the berth further from the gangway was already occupied by the time we arrived.
The classic approach to this problem is to face up-tide, get into line and slow right down until the tide walks you very slowly backwards into your berth - with or without the other boat in place, a crew member hops on to the pontoon and warps you in.
Because the shallow, muddy shore was so close, this was risky. Also, on several days there was an erratic, gusty wind.
The technique we ended up using wasn't very kind to the pontoon's moorings, but it worked - just. We went in head first down tide and used a spring to help stop the boat (and once, when the prop didn't open, as the only means of stopping).
A trusted and nimble crew member (sometimes me, but we took turns because it was so scary) took the stern line and a spring, tied to the mast and led through the jib fairlead block (slid up to its foremost position for the occasion). He stood outside the lifelines ahead of the shrouds, and jumped onto the pontoon as early as he could, slipped the spring round the most uptide mooring cleat he could reach and surged the line out, braking the boat's movement as quickly as possible, then tied off the spring and pulled in the stern line.
