Roll tacking in a keelboat is definitely something worth practicing and it takes a little while to get it right. In lighter winds using the crews combined and coordinated weight movements to help roll the boat through the tacks helps keeping the speed through the tacks and minimise lost ground.
Stepwise guide to roll tacking on a keelboat
First method – moving weight to support steering going into the tack
Crew is moving it’s weight in a coordinated at the start of the tack helping the boat steer through the tack without losing too much speed.
- All crew gathered at the leeward side
- All crew moving across to the old windward side causing the boat to straighten up generating additional airflow over the sails
- Helmsman steers the boat through the tack as the crew passes midship
- Tack completes and the crew is now all gathered on the new leeward side helping to create an optimal heeling angle
Second method – moving weight to help boat accelerating out of the tack
In this technique the crew is rolling the boat after the tack is completed to help it accelerate coming out of the tack.
- Crew on the windward side (this obviously assumes a little more breeze than in the previous example)
- Helmsman tacks the boat while the crew is still not moving
- The boat is on it’s new tack and crew weight all on the new leeward side creating the boat to heel
- The crew now moves in a coordinated way over to the new windward side and the boat accelerates due to the extra flow of wind created over the sails
What does the rules allow?
The main rules relating to roll tacking are specified under section 42 and I have copied an extract here:
42.1 Basic Rule Except when permitted in rule 42.3 or 45, a boat shall compete by using only the wind and water to increase, maintain or decrease her speed. Her crew may adjust the trim of sails and hull, and perform other acts of seamanship, but shall not otherwise move their bodies to propel the boat.
(a) A boat may be rolled to facilitate steering.
(b) A boat’s crew may move their bodies to exaggerate the rolling that facilitates steering the boat through a tack or a gybe, provided that, just after the tack or gybe is completed, the boat’s speed is not greater than it would have been in the absence of the tack or gybe.
Normally a keel boat roll tacking will not achieve higher speed coming out of the tack than it had going into the tack, although the loss of speed is less when roll tacking. For that reason none of the above mentioned techniques should be in conflict with the rules.
In a dinghy a well executed roll tack will give the boat a higher speed going out of the tack than it did before the tack and hence it’s more sensitive from a disallowed propulsion perspective. This clip shows the roll tacking of a dingy and the technique actually combines the two methods described for the keel boat roll tacking, i.e. the crew weight help accelerate the boat both going into the tack, and also once the tack is completed accelerate again.