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Go Back   SailNet Community > On Board > Boat Review and Purchase Forum > Sailboat Design and Construction > Tender
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Thread: Tender Reply to Thread
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Topic Review (Newest First)
11-05-2008 09:01 AM
Jeff_H Adam,

This is not a simple question. Speed is a product of many factors such as the relationship of the amount of sail area to the amount of stability, displacement and wetted surface, the efficiency of the hull form, rig and under water foils (keel and rudder), the propensity to roll or pitch which makes sails and keels less efficient, the effectiveness of a boat hull to deal with the colision with waves without losing speed and so on.

As SD aludes, there is a lot more to to the impact of beam than the sheer width of the boat taken at one point at the rail. More significant is whether the beam is distributed much of the way fore and aft (slow), occurs far forward in the boat, (slow), whether the boat has a narrow waterline beam when standing on its feet and a progressively wider waterline beam as it heels (fast), whether there is a hard bilge which generally adds drag and requires more agressive steering angles (slow), and so on...

Jeff

Jeff,
interested in learning more ,
when considering two similar boats , nearly same length overall and length at waterline, but a nearly two foot difference in beam. Is the narrower is faster more because of less water resistance and less because of an increase of waterline when healing?
Would the wider boat resist healing, or is the amount of heal have more to do with the righting moment, relative to ballast weight?
thanks for the feedback
adam
11-04-2008 08:26 PM
sailingdog Adam-

The wider boat may have more form stability, but that may or may not make it less tender than the narrower boat, since some of stability is derived from ballast position/amount and some is derived from the shape of the boat.

Also, a narrow boat may not be faster because it has less water resistance, it depends on a lot more than just beam. Things that may affect water resistance are whether a boat has a hard curve to the bilge or soft curves to the bilge, whether it is a full keel or a fin keel, etc.

A good book for you to read is Dave Gerr's The Nature of Boats.
11-04-2008 08:20 PM
adamtroyg Jeff,
interested in learning more ,
when considering two similar boats , nearly same lenght overall and length at water line, but a nearly two foot difference in beam. Is the narrower is faster more because of less water resistance and less because of an increase of water line when healing?
Would the wider boat resist healing, or is the amount of heal have more to do with the righting moment, relative to ballast weight?
thanks for the feedback
adam
10-16-2008 09:47 AM
Jeff_H I would like to touch on a comment in AdamTroyG's post above. AdamTroyG said that he had heard that "I was told: tender meant you'd quickly get your rail in the water, increasing your waterline and increasing your hull speed."

As has been explained above, tender describes a boat that does not have much initial stability. In other words a boat that is light on form stability so that it initially heels very easily. When you talk about initial stability, you are are normally talking about stability within a pretty narrow heel angle, perhaps up to 20-30 degrees of heel.

When you start talking about heel angles that are large enough to dip a rail, then you are really talking about the stability of the boat in a range where form stability is becoming less significant and stability that comes from position of the center of gravity.

AdamTroyG's quote, is not accurate for all or even most boats out there and for the most part only applies to the conventional wisdom surrounding 1950's-1960's era CCA/RORC rating rule type hull forms. These rules over penalized stability and waterline length. Designers exploited that loophole by producing boats that had long overhangs and poor overall stability through a range that was wide enough to allow enough of the overhangs to end up in the water that the sailing waterline length was increased over the measured waterline length.

Research has shown that these increased waterline lengths do in fact increase the speed that the boat can achieve in the heeled position over the speeds that would be anticipated based on the boat's static waterline, but the ultimate increased speed is smaller than that of a boat of equal length that had a longer waterline to begin with. It was also found that the boat that began with a longer waterline was able to more easily hit its hulllspeed and stay closer to hullspeed a greater percentage of the time, which in the real world is far more important to passage times than a throretical advantage that a boat with a short static waterline/ longer heeled waterline might gain under some rating rule.

So, to make AdamTroy's statement more accurate, "Boats of the CCA/RORC era tended to be tender, and also when heeled they extended thier sailing waterlines over their static waterlines, and thereby potentially increased thier hullspeed in certain windspeeds on certain points of sail."

Respectfully,
Jeff
10-15-2008 01:43 AM
JiffyLube
Quote:
Originally Posted by Giulietta View Post
Funny..where I come from, tender means the opposite..like soft...slugghish to sail, stable, slow, confortable.
I like 'tender' women...hehehe
10-14-2008 08:15 PM
adamtroyg Hi Dan,
I've had my 1973 Sabre 28 for two season. I also read Horner's review and wondered if "tender" was going to be good or bad. I was told: tender ment you'd quickly get your rail in the water, increasing you water line and increasing you " hull speed ". I've been on some catalina and hunters in the same range 28, 29 & 30. The Sabre is 9 feet wide the Catlalina 30 is 11 feet wide. I'll bet these boats width keeps them from being tender. Great if you need the space, but I generally beat them when we race.
let me know if you want any more info about the Sabre.

adam
10-11-2008 01:18 PM
sailordave
Quote:

tender adj 1: given to sympathy or gentleness or sentimentality; "a tender heart"; "a tender smile"; "tender loving care"; "tender memories"; "a tender mother" [ant: tough] 2: hurting; "the tender spot on his jaw" [syn: sensitive, sore] 3: susceptible to physical or emotional injury; "at a tender age" [syn: vulnerable] 4: having or displaying warmth or affection; "affectionate children"; "caring parents"; "a fond embrace"; "fond of his nephew"; "a tender glance"; "a warm embrace" [syn: affectionate, caring, fond, lovesome, warm] 5: easy to cut or chew; "tender beef" [ant: tough] 6: physically untoughened; "tender feet" [syn: untoughened] [ant: tough] 7: (used of boats) inclined to heel over easily under sail [syn: crank, cranky, tippy] 8: (of plants) not hardy; easily killed by adverse growing condition; "tender green shoots" n 1: something used as an official medium of payment [syn: legal tender] 2: someone who waits on or tends to or attends to the needs of another [syn: attendant, attender] 3: a formal proposal to buy at a specified price [syn: bid] 4: car attached to a locomotive to carry fuel and water 5: a boat for communication between ship and shore [syn: ship's boat, pinnace, cutter] 6: ship that usually provides supplies to other ships [syn: supply ship] v 1: offer or present for acceptance 2: propose a payment; as at sales or auctions; "The Swiss dealer offered $2 million for the painting" [syn: offer, bid] 3: make a tender of; in legal settlements 4: make tender or more tender; "tenderize meat" [syn: tenderize, tenderise]




Oh, and it also means a boat that isn't very stable. Or at least doesn't have a lot of INITIAL stability. For all the reasons others have posted.
10-10-2008 11:15 AM
Rockter Tender = wobbly.
Stiff = not wobbly.
10-10-2008 10:22 AM
eMKay ^^^^^^^^^^^^^^^
09-30-2008 11:28 PM
Delirious "Tender" is a derogatory term used by cruisers to describe a sailboat that has acceleration you can feel through your seat and may move well in light air. Usually applied to designs know as cruiser/racers or racer/cruisers. ("Unstable" or "Death-traps" is a cruising term for racing sailboats).

Our Pearson 27 threw herself on her ear to about 15ļ in much of any wind but hardened up solidly and would only heel a bit more thereafter. When you know it's coming it's not bad but we did startle a few guests who were used to more beamy modern or older heavy displacement sailboats.

And yes, that boat would broach and round up if you tried to stretch the full main and were too lazy to reef early (or were charging for speed). All boats are compromises.

Having raced Thistles the Pearson felt like a rock to us and we loved it.

"Tender" can be synonomous with "responsive". You don't call a car with sport suspendion "tender". Same concept. Sailboats are built to perform different functions in varying conditions. Choose wisely. ;-)

The Sabre 28 is a heck of a lot of boat in 28 feet. If you want long range cruising maybe not the best choice as it will suffer from being heavily provisioned and will not track well in heavy seas, but it will also harden up from the added weight and folks do take them all over. If, however, you want to pick of Catalina 28's during the day and sleep in a slip or anchorage at night it is a primo 28 footer.

You also have to consider that in the , late 60's, 70's and early 80's there was a handicapping system for racing that rewarded boats with overhangs or short waterlines and angled entrys. To get these boats to perform they had to quickly lean over, effectively lengthening the waterline and getting some lift from the wetted hull-shape. Some of the designs went too far and were not very capable cruisers at all. Nothing like the sensible race sailboats of today with their "surprise-detach" keels and twist away rudders. The rules changed and now you see beamy, fat arsed boats with bluff bows. Flat bottomed boats are not tender, but neither are they especially pleasant to ride in roused wave conditions.
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