Originally Posted by CT249
It's not just an Australian thing. The Americans have called movable foils as heavy as 7 tons "centreboards" since the 1800s (see WP Stephens etc). The CCA style boats like Finnisterre were called centreboarders, despite the fact that their centreboards were often quite heavy.
Farr called them "drop keels" in some places, "centreboards" in others and "lift keels" in others, all in the same publication (see their site, which contains scanned plans and descriptions from their old catalogue).
Actually the term "daggerboard" was originally used for pivoting centreboards designed by Linton Hope in the 1890s, which were shaped like a dagger (deep and narrow, straight on the leading edge and curved on the trailing edge) unlike the normal low-aspect centreboards of the day. So the modern use of the term is a distortion of the original use. And down here at the time, the low aspect centreboards were called "gins" for some unknown reason. So if there are specific names for different foils depending on their weight, it's not universal.
After all, there are dinghies that have metal centreboards and we don't call them "drop keels". In fact the early International 14s had 100kg centreboards; they never called them drop keels or lift keels despite the fact that they gave the boat quite a high ballast ratio.
Mmh, i think one should know what he's talking about.
Nowadays for me it' s out of interest how they named ballasted cenerborders under longkeelers in 1890 when no finkeelers existed..
Also the incorrect definition by Farr in the 1970/80 is obsolet, ' cause he didn'nt differ between boats wih internal ballast and partly , or non ballasted center- and daggerboards.
I don't want to put the blame on anyone, those days everyting was unknown, one could say new.
Today we are able to define all those appendages exactly.
With other words, historical definitions are historical , are partial, are defective, are obsolet.
For me a correct definition is a must, 'cause a liftkeel with the whole ballast ( say 1ton) is much harder to design than a "liftkeel" with only 200 kg. Unfortunately the boating industrie tries to sell these boats with ballasted daggerboards and most of the ballast in the bilge as " liftkeeler".
See Parker 275: http://www.yachtsnet.co.uk/archives/.../parker-27.htm
The boat is ballasted with 2500lbs, only 300lbs are in the ballasted daggerbord.
To reach sufficient righting moment the amount of bilge ballast is very high.
Compared with her bigger sister , the parker 325 we see the difference.
She has a real liftkeel , all the ballast is in the bulb ( in this case a horizontal wing for standing upright).
The 325 has a ballast of about 2400lbs. Because her ballast is much deeper she's a stiffer boat with a much smaller ballast ratio than her little sister the 27.
Conclusion, boats with real liftkeels are lighter, thus faster, and stiffer. http://www.yachtsnet.co.uk/archives/...parker-325.htm
The drawback-- such a keel needs hydraulic for lifting, while a ballasted centerboard of about 300lbs can be lifted manually with a winch or e- motor.
Swingkeels are ballasted centerboards---pivoting keels retracted into a trunk. Most of the ballast of these boats is in the bilge, or casted iron directly bolted under the hull ( protection when drying out).
Best examples are the Southerlies, electric or hydraulic driven swingkeels of about 1000lbs and bilge ballast of about 4000lbs ( it differs according to boatlength; southerly 95; 100;101; 105, 115; 32;35.....)
All the Southerlys have fixed ballast in the form of a wide 'pancake' iron casting which acts as a grounding plate, through which drops an aerofoil section cast iron swing keel, which pivots on a stainless steel bearing, and is raised and lowered by a hydraulic ram - in all but a few early boats this is powered by an electrically driven pump, operated from the cockpit. There is though a hand operated back-up. The keel can be locked up or down. The photo at left shows the keel of a Mk I down with the yacht in slings http://www.yachtsnet.co.uk/archives/...therly-115.htm
Kielschwerter ( there ain't no english word)
These boats havebiron stubkeels with an integrated centerbord . In earlier days the centerboard was a simple steelplate, nowadays it's out of GRP and profiled.
For obgaining the same righting moment as her finkeeled sisters , the stubkeels are much heavier. The boat is slower and of course the appendage is of poorer quality such a boat will not point so high as a finkeeler.
Today all the modern Kielschwerter have little wings for standing upright when dried out. Mostly they have double rudders ( vulnerable -- same draft as the stubkeel.
These boats are NOT supported by their rudders when dried out !
Similiar to bilgekeelers they stand only on their keels when dried out. the balanced non-skegged rudders only touch the the mudd/sand.
Beneteau, Jeanneau , Delphia..... http://www.google.de/search?q=benete...gcxZCS6zDNm6M: http://www.google.de/search?q=benete...R6yDt3jwZLyYM:
As i've mentioned before, much too often thhese Kielschwerter are praised by yards, sellers and brokers as "liftkeelers".
As we've learned, a real liftkeeler performs much better than a Kielschwerter !
Under the hull pivoting keel http://www.rm-yachts.com/en/1st-lifting-keel-installed
I'm sure you've noticed it, this is NOT a lifting keel as the yard claims.
The pivoting keel has a sort af bulb at the tip and a very effective high aspect ratio.
These keels normally have very much draft. For standing upright ,when drying out , the boat needs legs, sometimes they are telescopic and integrated. http://www.google.de/search?q=malang...DkP72oqjyCP3M:
Centerboarders with internal ballast
All Ovnis and nearly all polish trailersailer have non ballasted centerboards and bilgeballast, here lies the main reason for poorer upwind performance. Together with little daggeboard area and high freeboard for max. volume inside we get .... http://www.google.de/search?q=viko+2...OXU1KACF2zmXM: http://www.google.de/search?q=viko+2...vSLKi9T9-JwbM: http://www.google.de/search?q=ovni+3...3JDCSyebvxDGM:
for real shallow water cruising/sailing all the above bespoken appendages must be bulletproof. that's s a real challenge for the designe and costly for the yard.
I' m not talking about occasionally drying out and smooth beaching.
I' m sailing about 40% in shallow waters, since 1978 with own boats.
I've tried , built , rebuilt, modified and designed dozens of centerboards, daggerboards, liftkeels, transom hung kick-up and cassette rudders , balanced low aspect ratio double rudders.
The , no , my disadvantage is that all these appandages are in a niche.
Common people wanna have variable depth for trailering and perhaps for occassionally drying out.