Saturday, 25 February 2017

Flopper Stoppers, revisited

I’ve been studying flopper stoppers and various ways to prevent the boat from rolling uncomfortably with swell.  We plan to anchor out a lot this summer and the Med is well known for rolly anchorages.  I want to avoid any system that requires hanging something out from the side of the boat using the boom or spinnaker pole.  This is certainly the most stable configuration, but if you leave the system set up overnight, you have to put a light at the end of the boom to signal its presence.  We also suspect that many or most of our anchorages will be very crowded, and having a system poled out while inexperienced “credit-card captains” try to squeeze into tight spots right next to your boat gives me nightmares.  I want something that is simple to install, something I can leave installed while going ashore without worry, and, most importantly, something that can be uninstalled quickly in the dark at 2 a.m. when you have to leave the anchorage in an emergency 

The photo theme is "Paris by the Sea, part 2": nautical-related art and artifacts seen around Paris.

Arsenius' planispheric astrolabe (1530), Museum of the Centre National des Arts et Metiers, Paris.

I’ve only found 2 systems that don’t require poling out:  the Mexican hat cones and the butterfly pole. 

The Mexican hat or inverted traffic cones system is a series of plastic cones that look like flattened traffic cones (or sombreros) that you hang over both sides of the boat.  With the hats pointing down, they offer little resistance against the water as they descend, but as they are pulled up with the roll of the boat, the hat captures the water and resists the roll.  For Mareda, we would need a series of 5 on each side with a weighted line.  There are a couple of problems:  storage is not so simple for such a bulky configuration, but more importantly, there is a problem of inertia that reduces its efficiency.  As the boat rolls and pulls the cones up, they resist but are still displaced upward a bit.  As the boat rolls back in the other direction, the cones sink, but generally not as fast as the boat rolls (unless you have a large amount of weight on the line, and I don’t particularly want to heave 15 kilograms / 33 pounds up by hand at 2 a.m.).  This means that by the time the next roll begins, the hats have not fully descended and there is some slack in the line before they catch.  The cones alone cost 180 Euros, to which you have to add line and two 10-12 kg weights.

Another astrolabe from the CNAM museum whose name I entirely failed to record.

The butterfly pole is something I’ve read about elsewhere but have only seen developed by our local Mediterranean sailing guru, Pierre Lavergne, based on his 15 years of sailing in the Med and having tried everything.  Last year, Pierre convinced us that a riding sail was a necessary piece of equipment to avoid the windshield-wiper effect that stresses boat, anchor, and crew in windy anchorages.  That simple sail greatly improved the quality of several anchorages this past summer.

Sundial, Cluny Museum of Medieval Art, Paris
In French, Pierre’s system is called the “parahoule” and it consists of a rigid pole of three sections with a total (adjustable) length of about 3 meters (9 feet) with large articulated spade-like blades fixed at the bottom.  The pole is fixed to the balcony or stanchions and rails.  As the boat rolls towards the swell, the butterfly blades fold to reduce resistance and the rigid pole ensures that there is no slack in the system with no need for weights.  As the boat rolls with the swell, the blades fly open to resist the roll.  By putting one butterfly pole on either side of the boat (and the poles can be placed anywhere to balance the swell coming from directions other than straight a-beam), the roll is significantly dampened.  Pierre says it won’t dampen out all swell completely but will make the difference between a gentle rocking and a sickening sleepless night.  Pierre’s system costs 165 Euros, all included, for 2 poles, the system breaks down to 1 meter / 3 feet long, and weighs about 7 kilos / 15 pounds, easy to transport in our luggage.  The system can be quickly hauled out of the water and fixed along the life lines while sailing between anchorages – no need to completely disassemble and store it below.

Pierre's web-site is a goldmine of information (best if you read French) and he has fully described the parahoule on a companion site.  I’m eager to try this out (well, I would rather have perfectly calm anchorages, but…).  We'll make a full review as soon as we have some experience with it.

One of the world's largest Topazes from Brazil.  No, this has nothing to do with navigation, but it sure is pretty.

Posted on Saturday, February 25, 2017 | Categories: