Appropriate Freeboard

viking boatHigh freeboard improves buoyancy with no decrease in hull speed. Sailboats at rest with low freeboard only look faster than many of their high freeboard counterparts. Unless the boat has the general shape of a log, the heel of the vessel increases the freeboard presented to the wind. High freeboard presented to the wind when heeled can cause excessive lateral drift which results in more tacks during an upwind race.

In my cruiser, it takes a lot of wind (17 MPH +) to observe lateral drift when close hauled. When close, the freeboard presented to the wind is minimal. That plus the fact that Mac26x cruisers have about the same amount of freeboard as a Catalina 30 has me convinced that the freeboard in my vessel does not slow her down. Murrelet got her name from the marbled Murrelet a small sea bird that rides high when in the water. You do notice the high freeboard my cruiser.


It is a waste of time to try to update a duck. A duck is naturally beautiful with simple lines. If you (modify it) then you will only have proven to the world that you were blind to its simple beauty in the first place.

Ference Mate Best Boats To Build Or Buy pg 78 One For The Eyes BCC


Image080Low freeboard made sense during the age of marine hunting when it facilitated the work necessary to process the catch or to row. But with low freeboard a modest amount of heel will put the rail under the water. This slows the vessel down considerably and in the extreme can sink the vessel. It is a safety issue.

Low freeboard sailiing vessels are considered appropriate for inland protected waters. These vessels are fine for pleasure use. Pleasure boats – by definition – are toys, and they are not expected to be operated outside of the bath tub environment of a small lake or bay. I do not consider Murrelet a toy. She is a recreational vessel designed specifically for ocean use with appropriate freeboard for that purpose. In addition, and unlike some sailboats sold for ocean use that have low freeboard when at rest, the freeboard on Murrelet and her kind does not vary much when on heel under sail.

 

A few years after purchasing Murrelet, a group including my sister and her husband and my wife and I chartered a couple of 40 foot monohulls for a few weeks of racing and cruising in the British Virgin Islands. The Florida based Beneteau 402 center cockpit sloops were built in South Carolina specifically for the hot climate prevalent to their cruising grounds. In my opinion, the freeboard was determined by the layout of the interior of the vessels with the notion that head room would contribute to ventilation. We discovered in sort order that the vessels were human steam oven’s nonetheless. Unfortunately the center cockpit was two small for laying down (as is the Ms), so we made due below decks as best we could. The notion that cruising vessels have higher freeboard because of the need for ventilation did not hold up to our observations. It is not possible to have enough freeboard in a cruising sail boat to generate the head room needed for ventilation in the humid tropics, unless perhaps if the deck is made of porous wood. And of course excessive freeboard can be a problem.

For a sailboat, low freeboard on the lee side can cause flooding. But the high freeboard on the windward side can also be used like a lever by the wind to flip the vessel over (an obvious stability concern for a multihull). In a moderate or strong wind, a cabin cruiser can be very difficult to maneuver owing to the amount of wind that hits its hull. In 2003 Murrelet was Shilshole shuffeled to a slip providing a grand view of this issue.

Shilshole Shuffel

The Shilshole shuffel is the term applied at the Shilshole Marina to describe frequent but often temporary changes in slip assignments owing to the difficulty of managing sub leases. If I were running things sub leases would not be allowed but in anycase I so enjoy watching large underpowered cabin cruisers and even sailboats pull up for fuel and depart when the wind is blowing, that my shuffel was made permanent.

The desirability of a real engine, rather than a sailboat kicker on a cruiser with freeboard worthy of ocean craft was obvious from Murrelet’s 2003 summer-post-shuffel perch. Owing to what happens in windy conditions, you do not want a cockpit enclosure rigged on a vessel that is under powered. I will not soon forget the large cabin cruiser that had to exit Shilshole about the down wind breakwater, the captain complaining that the fully enclosed vessel just would not turn upwind in the amount of harbor available. The following X cruiser has been fitted out with a full cockpit enclosure.

 

back enclosure front enclosure
room to move forward interior

The Wind’s enclosure, while providing ventilated sleeping quarters for a couple of crew larger than 6 foot tall does not allow the boat operator to stand upright behind the wheel as would be the case if the enclosure extended past the backstay or the boom were higher as on the Mac26M.

standing room enclosure<br /><br /> under full sailOther Mac26x cruisers sport enclosures with standing head room that restricts mainsail use. The Wind’s enclosure included zippers in the dodger viewport that allowed opening for visibility. Hence crew could stand under the dodger and operate with an autopilot remote or the captain could operate while sitting down at the wheel with crew spotting. Zippers opening from the centerline allow the mainsheet to extend through the enclosure so that the mainsail can be deployed. A viewport in the enclosure top for checking mainsail trim and the wind indicator would be ideal. For sail handling during a race you would of course remove all the enclosure parts (including rain dodger). When weighted down for an extended cruise, and given the 50 hp engine, I forsee little problem in the configuration. Murrelet should be just as fast and manuverable with the enclosure as without assuming proper weight distribution.

Weight Distribution

Weight distribution is important to the speed a vessel can achieve. For the fastest speed while motoring, weight should be low and to the centerline. Think like a motorcycle rider or an ice skater to see this. It is easily observed on a speedboat by having crew sit at different positions during runs at wide open throttle (WOT) and noting speed by GPS.

motor bike riders make good crewThe notion that low freeboard sailboats are faster than similar sized higher freeboard competitors is supported by this weight distribution observation. Crew with no place to be except low in the boat allows greater speed.

However monohull sailboats heel where a speed boat will not, and unless the sailboat has the overall shape of a log, the heel creates more freeboard on the windward side, and less on the lee. The distance from the water to the rail is defined as freeboard. Analysis of the MacGregor Classic, M, and X illustrates.

Start with a Mac26 Classic and its low freeboard. Crew will stand or sit lower on deck than they could ever position themselves outside of the cruiser on a Mac26M.

 

Mac26 classic - crew<br /><br /> must be low to water

On a Mac26M weight at the higher level of the deck when forward, and assuming hull shape roughly equivalent, means the cruiser is less stable than the Classic.

That condition is not necessarily bad. In fact in light wind it is beneficial. On a sailboat with a Classic or M style hull, that is light enough for crew weight to make a difference, crew will move forward to a point where the vessel will lean and, if the leaning is to the lee, sails will gain shape by the force of gravity alone. In very light wind – often what appears to be no wind – the light displacement sailboat with gravity filled sails requires just a small puff of wind to start moving forward. Only a small puff is needed because none of the energy in that wind is needed to lift the sails.

 

Mac26m in forground; Mac26 classic<br /><br /> behind her

So the Mac26m, being more responsive to crew weight on the foredeck, should, assuming hull shapes are more similar than not, out sail a Classic in light air when crew is positioned there. This is a situation where the higher freeboard makes for a faster sailboat but at the cost of a manufacturer’s safety restriction. If crew were restricted below deck, the M would have no speed advantage. When on deck, the weight of crew can tip her over.

Mac26x on lift showing belly and<br /><br /> Mac26x in water, belly providing foredeck stability exceeding the M and classics

Now consider the X cruiser. Her freeboard is equivalent to the M’s when at rest. But as crew move forward and the vessel leans, the flair in the bow (called a power boat belly by the manufacturer) at more than a 15% heel provides counter acting buoyancy and hence the X gets the speed advantage over the Classics with no safety restrictions.

The X cruiser, because she is not restricted to ballast only operation, can also drop 1,400 lbs of weight, this reducing what is called dynamic stability and making the boat more responsive. In effect the draining of water ballast moves weight from off the centerline of the motoring cruiser, this contributing to speed as discussed above. The mechanics are not unlike the spinning figure skater who brings her arms to her chest to increase the speed of her spinning. The water ballast so drained out also provides extra flotation which can be used to carry provisions for extended cruising, provided those provisions are stored and secured properly.

Freeboard Disadvantage and Advantage

European builders tend to tout the open stern not as a swim step but as a simplified means of boarding when Med mooring. Either way it is hard to imagine any new boat with a conventional transom anymore. John Ketshmer Boat Test: Southerly 110 pg 44 Sailing 2005 April


low freeboard stern with<br /><br /> room for loading a<br /><br /> person from the waterMurrelet rides high but not excessively, not without grace, with inherent beauty by my eye, and unlike many sailboats the freeboard doesn’t vary much when heeled. The most important disadvantage of high freeboard on a recreational vessel involves retrieving a MOB (man overboard). Many ocean sailboats carry life slings which are a tool used for hoisting MOBs. Modern designs (like Murrelet) have low freeboard at the stern that make unnecessary life slings. The M if mounted with a 50 hp motor does not have this feature. The Mac26m and Tattoo have contemporary rather than a modern design more suited for a small sailboat kicker engine. A 50 HP motor blocks entry from the stern, and hence Ms should carry a life sling when fitted out with 50 hp or any large size engine.

In addition to stability, there are a couple of other benefits to high freeboard. First, at anchor, a certain amount of windage is a good thing. Some sailboats and even power vessels prone to sailing or skating at the anchor will put up a small sail at the stern to lay the boat quitely to the wind. Keeping the boat as still as possible at anchor is a good thing because it minimizes the possibility of anchor drag, rode chaffing, or smacking another boat. The Mac26x cockpit enclosure, partially or fully deployed in concert with a dampening weight, such as second anchor hanging straight down from the bow, keeps Murrelet from skating even with the foils retracted. A similar effect is gained by tying off a lunch hook to the stern rather than to the bow and forgoing the dampening weight. Windage explains both anchoring observations. Second, I am able to sail Murrelet bare polled using the hull as a sail. This is with maneuverability. The following table is related to the above discusion:

 

MPH – Beaufort Knots Sail Plan for Murrelet (not necessarily appropriate for other X vessels.)
0-4 – 1 1-3 Full main sail, and Genoa. Patches of ripples.
4-7 – 2 4-6 Full main sail, and Genoa, consider water ballast, less Genoa Overall ripples.
8-12 – 3 7-10 Full main sail, and Genoa, and water ballast Small waves.
13-18 – 4 11-13 14-16 Intermediate reef main and full Genoa – planing mode Intermediate reef main sail & 110% – 120% of Genoa longer flatter waves.
18-24 – 5 17-21 Reefed main sail & 80% – 90% of Genoa Few whitecaps.
25-31 – 6 22-27 No main & Genoa rolled out more than jib size overall whitecaps.
32-38 – 7 28-33 Lower end, Genoa only in storm jib size Sail the hull, consider motor sailing, go with the flow. Small Craft Advisory, you will see sailboats but very few cabin cruisers.
47-54 – 8 41-47 Should have motored to harbor. These are fast sailboats capable of reaching harbor by sail or motor before such a blow.Remove enclosures. consider dropping mast. Close hatches. Sail hull. Gale Warning. You will see few boats. Wait it out. Write book.

High-Charged Ship

100_0699The Jesus of Lubeck was a typical high-charged ship of the 16th century. She was a German-built carrack converted to a warship by the English and leased as an armed slave-ship. She made two voyages involving a triangle from Sierra Leone with goods for exchange in Africa for slaves that were then sold to Spanish in the Caribbean for sugar cane and other produce. The trips involved battle with the Portuguese off the African coast, who wished to maintain their monopoly in the African slave trade. But it was the Spaniard’s desire to restrict trade to their own nationals which caused the sinking of the vessel.

100_0695On a third voyage, Jesus of Lubeck was being provisioned at San Juan de Ulloa, where she took shelter from a hurricane in the Gulf of Mexico. She was ready for voyage home when the Spaniards attacked. She and her companion vessels (one commanded by Francis Drake) were able to hoist anchors, but only the companion ships were able to escape. The Jesus of Lubeck was to slow and unhandy. The loss of the Queen’s ship lead to a review of her design. It was believed that the build up of several decks into high castles overhanging the stern and on the bow, while not hindering speed going down wind, were of concern on other points of sail. These high-charged attributes were removed in John Hawkins’ experiments using smaller vessels to test if a ship with lower freeboard could point higher into the wind.

IMG_3704The forward castles were removed from the prototype “low-charged” vessels (the Bull and Tiger), and the aft castles were later reduced as well. The first low-charged vessel (the Foresight) pioneered by John Hawkins was a radical change. The change was implemented on warships from 1570 on. The low-charged vessels were called English galleons and were used to defeat the Spanish Armada in 1588.

Galleons

100_1361Galleons, while being the result of experiments in lowering freeboard to see if pointing could be improved, had square rather than rounded sterns and a length to beam ratio of 3 to 1 rather than 2.5 to 1 which was common in the high-charged ship (also know as an expanded English Cog). Today it can be seen that those changes had more to do with speed than freeboard.

 

3 thoughts on “Appropriate Freeboard

Leave a Reply

Your email address will not be published.