Stop the Flop – make yourself a flopper stopper...

Or roll stabiliser – another name for flopper stopper. One of boating’s most uncomfortable experiences is to be in a windless anchorage with a swell surging in from some meteorological disturbance below the horizon. Given some wind, a boat will tend to lie head into it. In windless conditions most boats prefer to align themselves beam-on to any wave action, rolling hideously as they do so.

Fortunately, a practical remedy is possible. You need a flopper stopper – a somewhat ambitious term for what should more accurately be described as a ‘roll reducer’ or, more pretentiously, a ‘roll attenuation device’.

There are various proprietary products on the market but here’s one you can make yourself in just a couple of hours or so. It’s not an original idea by any means but it works well as I can testify, having made a few over the years. The lastest (right) does excellent service on my 12m sailboat. Quite apart from its effectiveness, it has the considerable virtues of mechanical simplicity and a conveniently stow-able flat shape.

The principles behind its operation are illustrated right. This is how it works:

A triangular plate, weighted in one corner, is suspended underwater as far outboard as possible – typically from the end of the boom or spinnaker pole.

A: When the boat rolls towards the flopper stopper the weighted corner drops and the plate dives, almost edge on.

B: Then, as the boat begins to roll upright again, the three-legged harness snaps the plate horizontal and the sudden increase in drag dampens the rolling and improves comfort considerably.

The construction details are simple enough to dispense with a lengthy explanation but below are a few points worth noting:

• Although I have heard of folk using plywood, ideally the plate should be non-buoyant. I used a sheet of glassfibre (about 8mm thick) but equally practicable would be aluminium or steel.

• The flopper stopper should be sized to match the boat – the exact dimensions being a bit of a guess really. The plate shown here had sides 700mm in length before the corners were rounded off to help protect the topsides if it ever clattered against them. In truth it could have been a little larger.

• Any type of weight will do but it needs to be fairly heavy if the plate is to dive without delay. The one shown in this article is a 5lb dive belt weight but I was tempted to use a spare zinc anode.

• Don't skimp on the rope harness. Here I've used 10mm three-strand polyester which, of course, is easy to splice. Notice that I have not trimmed and melted the strand ends, preferring to leave them long and soft to handle.

• If possible the plate should be suspended below any surface wave action. The deeper the better. It helps to lead the attachment line back to the cockpit so depth adjustments can be optimised, particularly in tidal waters.

• If using a spinnaker pole, the topping lift should be rigged to the pole’s end (as shown above) not the usual mid-length point. This is because the vertical snatch loads can be considerable and you wouldn't want to bend or break the pole.

  ---

  FREE DELIVERY!
  

  Get extra keen discounts and beat expensive shipping costs by buying books through this site! The free delivery service applies to most established destinations worldwide.

  
  

  Click the link below to see what's on offer.

  Buy now!