How to Spring off the Dock with a Catamaran

Next week we’re going to Tonga and the island of Vava’U for a week long NauticEd Flotilla sailing trip amongst the archipelago. After a rainy and relatively cool winter in New Zealand this year its going to be a welcome and fun trip. We’re bareboat chartering three catamarans from the Moorings. 21 adults and 3 three children aged 2, 3 and 6 are coming. Correction that makes 24 children I think by the excitement and way every one is acting so far. We’re looking forward to doing some excellent sailing, fishing, swimming in warm water, snorkeling under the rock wall into Mariner’s cave and maybe have a few lovely glasses of red wine under a warm evening sky. So in light of catamaran sailing then I thought this week we’d review a method of getting a catamaran off the dock when a difficult wind is blowing onto the dock. We needed to use this in the British Virgin Island last year and with some whacky wave action we also had to time it right. It’s just as well we used this method because, with the waves, some serious damage could have occurred.

Using a spring line to get off the dock with a catamaran

The concept is pretty simple and effective. First tie a dock line from the front of the boat to the  dock towards the aft. Then turn the helm all the way towards the dock and engage the out side engine in forward. The thrust from the backward wash of water as depicted by the arrow onto the turned rudder plus the force moments from the outer thrust and inner dockline will act to turn the back end of the catamaran out away from the dock. You must position a crew member with a dock fender to hold it between the boat and the dock. When the boat is turned out a significant amount, you can engage reverse but make sure it is more than 45 degrees out, else you can be in trouble with the wind  pushing you back onto the dock. Once in reverse, turn the helm the other direction to get the boat moving in the right direction. Wait until the boat is a significant distance away from the dock before you decide to engage forward and swing the boat around otherwise the back quarter of the boat can broadside back into the dock, especially if the wind is strong.

You can apply a little reverse thrust to the dockside engine but keep it so that the tension remains on the dock line. The method of using the dock line rather than just opposing engines turns the catamaran more effectively when operating close to the dock because the  dockside front quarter is essentially trapped thus a simple rotation won’t work.

Make sure that the dock line is arranged so that it is tied to the boat then looped 1/2 turn around the dock cleat then back to the boat. In this manner the crew member managing the fender can, at the right time, release one end of the dock line and pull it back around the dock cleat to retrieve it – all the while standing on the boat as it pulls away from the dock. Make sure the end has no knots in it. Also ensure the crew member understands not to release the dock line too early because they will not be able to hold against the thrust force.

Obviously this concept works similarly for monohulls.

Full concepts of maneuvering sailboats under power, sailing rules and catamarans are covered in these two NauticEd sailing courses.