Has anyone taken the brakes off a C16?

[Citroen/Dave]

I'm a Citroen car nut  (DS 21,   1955-75 ) which makes me very interested in aerodynamics amongst many other things.  In my professional career as a geologist I made 30 mechanical changes to a state-of-the-art drill rig, two that may have changed the industry. 

While sitting at my marina near Reagan Airport and contemplating things I need to do when the purchase of a tired C16 is completed, I appreciated the winglets that finish the aerodynamics (even retrofitted) to many passing jet aircraft.  While I am not proposing winglets to the C16's stub keel -  we are not race fanatics -  it occurred to me that the C16 might have a correctable problem. Has anyone ever added couple of inches to the bottom of the stub to take the brakes off?  The turbulence of the stub must be significant.  Perhaps someone who does not trailer might give this serious thought.  For that matter raising a C16 a couple of inches on a trailer should not be that much of a deal.  Someone could find the ideal profile but I suspect that just faring in a curve from the beautiful keel profile would have a noticeable effect.  Some additional insurance against breaching the keel by impact would be another benefit.  I see that many C16 owners already have a depth finder installed if that additional draft is a concern.  Just a thought for a winter project.  How often does anyone stand a C16 on its stub, anyway? Might be a good time to add some lead where the weight belongs.  By the way, I have gained some sitting foot room comfort by removing some of that concrete soil ballast I mentioned in a previous thread.  That makes the cabin much more livable.  I was going to add some lead internally but now I'm thinking of glassing it under the stub.

[Bob23]

I'm not sure that on a sailboat with a 5+ knot hull speed, that would make any difference. Also, wouldn't you be adding more wetted surface?
bob23

[Citroen/Dave]

Bob,

I agree that hull speed is the max, regardless, unless we add a bulb in the front and "planning tabs" in the rear to gain boat length. I don't propose such changes. What I am thinking is about all those slower sailing conditions where less hydraulic drag will separate boats. 

Also, I read where the C16's have a slow speed stall issue.  Might the stub keel be stalling earlier, just like the pre winglet airliner wing that stall earlier? 

Dave

[skip1930]

Our friend sails a Hake mf'g. [ Mr. Hake use to be employed at Hutchins ] Seaward of about 28 foot. The boat comes in two keel configurations.
One is a long vertical keel with no horizontal fins.
The other is a short keel with horizontal fins.
The keels can be raised and lowered, but that adds nothing to the story here.
And the 'fins' add to the cross section so push more water and hence slow the boat down?

Both keels displace about the same amount of weight, about 15 lb for every 1 lb at the top-o-mast. Don't ask me how anybody came up with that figure. One would have to define the top-o-mast and where the weight is...no matter.

The horizontal fin part was to reduce the keel draft wasn't it? I think the aerodynamic look to the keel was for a sales talking point. Not so much about lifting the boat, after all she's a 7 knot boat.

God bless the French...one 'Frog' mf'g. holds the wheels on with only three lug nuts, and Citroen has suspension that makes caring a spare un-necessary, plus the car squats down over time, and puts the V-6 in backwards facing the firewall, with the transmixer out front where it can be sheered off on parking concrete barriers.  Like SAAB. And then that single spoke steering wheel...just where is one to hang his or her thumbs? When it senses rain the wipers turn on...or the wipers turn on when she bounces over a bump just right. Oui?

And dummy me. I drove a Hotchkiss...An English engineer and a French coach builder...with bolt together cast aluminum frame [ !! ] engine in backwards, and suicide doors. She was a fine saloon indeed.

Then I drove a dozen more bloody British motorcars..never again.

skip.


This one I named ZIGGY. Good for 152 mph at 6750 rpm.  Double six saloon.




This one was FUN! But not so speedy.

[kickingbug1]

   well at least the healey has a good old ford v8 not a god awful multicarb six (a tinkerers dream). in regards to the keel question. didnt hutchins put a centerboard in the last of the 16s to help them point better (much like the legacy). while we are on that . does anyone sail one of those centerboard 16s and do they really point higher?

[Citroen/Dave]

During my career as a geologist for VDOT, I got to see a lot of bridge; I helped design the bottom half of bridges based on drilling to find support materials for piling or spread footings.  Most bridge pier foundations, piles or spread footings, are capped with a rectangle of concrete lying parallel to the current with the pier on top.  The shape of this concrete box has troubled me for a long time.  It is about the worst hydraulic shape to put in a river: bridge foundations cause bridge foundation erosion!

One notable case was a bridge built years ago in southern Virginia.  It was constructed with one pier in the river.  Not only did that one pier footing cause islands of boulders to accumulate down stream from the rectangular footing, the venturi effect between the two banks cause so much erosion at the banks that the two adjacent piers that were built in the flood plain became water bound. Now three piers in the river, and constant removal of the sediments building up in front and downstream of the original pier in the river. The hydraulics of the river has been ruined with property owners downstream watching meanduring, man caused, eat up their pasture land.

I was able to interest bridge engineers in improving the hydraulics of bridge piers but the contractors were not interested in the forms that would be necessary to shape a hydraulically less offensive shape.  The shape I proposed was very similar to the cross section shape of the C16 stub keel. By eliminating high pressure and adjacent low pressure areas caused by the rectangle,  fast moving water can be tamed to a more constant speed: erosion can be greatly reduced by moving the transition from higher to lower pressure areas from the contact with the river bottom.

Thus my interest in removing the squared off bottom of the stub keel of the C16.  I feel it would be a worthy project to hydraulically round off the bottom with a shape that would blend into the contors of the keel cross section.  Not winglets that some boat designers have experimented with but rather a rounded shape that would eliminate the turbulence and resulting drag.  That shape viewed from the side will look much like half the crosssection view of the keel, but probably not as thick.

[Citroen/Dave]

Re: bridge foundations.  I did succeed in getting the my bridge design group to stop putting piers in the rivers, but had to give up the VDOT sponsored barge/drilling/boating adventures . . .

Skip,

The attached link will take you to Citroen features of the 1955-75 DS Citroen that all manufactures have copied, usually rather poorly: http://citroenvie.wordpress.com/2011/10/11/ds-features-%E2%80%93-automotive-pre-imminence/ .  This was Citroenvue's [Citroen Car Club of Canada] second attempt at posting the list and the list is a little broken up, sorry.  Follow the link backwards to the article, "Back to the Future" for more Citroen history and an explanation of how the DS features worked. It amazes me as to how the automotive industry, world wide, copied so much technology, so poorly.  For example, power assist steering rather than powered self correcting steering.  Have you ever blown a front tire with you hands off the steering at 115mph?  With the Citroen you can apply the brakes, if you like, still hands off, and come to a  safe, controlled stop.  Read more . . . I am proud of how this series of articles turned out.

Dave

[Bob23]

Dave:
   I've been following this thread with much interest. In hydro-dynamics of our Compacs and how to improve them. And in Citroens. Back in the early 70's, I was employes as a foreign car mechanic back when one could distinguish between American and foreign cars. Otherwise known as the good old days. I'd like to be able to say I was open minded enough to apreciate the Citroen but I don't think I was. Truth is, we rarely got one in our shop, catering to mostly VW's, Porsche's,  Volvos, Saabs and those wonderful British Leyland cars. Toyotas and Datsuns were kinda rare but getting popular. Honda was just showing up.
   I really liked the simple genius  behind the air-cooled vw's and thus owned 14 of 'em. Wish I still had my old 1956.
   My Compac 23 sits on her trailer on the flat bottom of her keel. While I agree with you that rounding that off might help performance, it would kinda leave me in a bind as to how she'd live on her trailer. The 16, while sharing the same hull and keel shape, is quite a bit lighter (1000 #) compared to my 3000#. I guess one could support a 16 by her hull bottom but not a 23!
   Funny about the bridge foundation shapes. One doesn't see many rectangular shaped fish, does on?
   Keep up the good writing,
Bob23
   

[Salty19]

While I commend the engineering prowess (I'm a technology engineer myself), IMO don't mess with it. You'll not gain more than a small fraction of a knot in speed. Not enough waterline length.

Get a foiled rudder, new sails ( including a 155% genoa), a boom vang, balance the rig and learn to sail the boat. You won't believe the difference.

Rounding off the keel may sound like a good idea, and it may very well be, but think about the boat sitting on the trailer too.  
More surface area the better to distribute the weight.   Another issue..the keel is designed to kep the boat moving straight ahead, resisting sideways movement.  Would a more rounded profile hurt that?  I don't know, but less lateral resistance would likely be the result.  The hull is not a bridge footing, that is certain.

If you still think the boat is too slow after the above modifications, perhaps a more racing oriented design would be best?  Keep in mind you can't have it all in a boat--they are collections of compromises.

On another note, I haven't seen a citroen in a very long time.  I think the last one I saw was in Europe. I always thought they were pretty cool!!!  

Here's my fun car, just replaced an MR2.  Not terribly quick but handles curves like a Ferrari.


I

[kickingbug1]

   you know i tried to get into one of those blue things once. for me it was akin to a size 18 chubby trying to fit into a size 10. in regards to the 16. im with mike on this one, dont mess with it. if you want speed you need another boat.  i have had and have sailed faster boats in the past but i wouldnt trade my 6 knot com-pac for any of them. cant say that i have ever seen a french car that i would own. i already have a boat anchor.

[Salty19]

Kick..but it has 30,000 feet of headroom!!!   

[Bob23]

We all know that our Compacs are not racers but one is obsessed with efficiency like myself and maybe Citroen Dave, it's hard not to think of ways to improve the speed and handling. That for me is one of the essences of sailing...trying to figure out how to squeeze every last 10th of a knot out of a boat. And I don't even race!
Bob23

[Citroen/Dave]

Salty 19,

As previously acknowledged, hull speed is function of waterline length; no real chance to change that on a C16 and I would not want to try to change her lines.  I'm looking for better performance below hull speed, the range where we do much of our sailing, at least in the waters I hope to sail.  The addition could be solid or cored fiberglass, with encapsulated lead, that will stand the stresses of standing on the trailer.  I would remove all the accessable concrete and back fill with an expanding hard foam plastic to make the keel leak proof in the event of a hard impact.

Bob,

Thanks for your kind comment.

All,

Did anyone read the "Back to the Future" articles with the Citroen features page?  Anyone passionate about the ComPacs will appreciate the engineering brilliance of the several gentlemen that designed the DS mostly under the German occupation.

Dave

[capt_nemo]

Dave,

To improve my Sun Cat's sailing performance in light to moderate air I added a homemade Nylon Drifter that made a significant improvement in performance. And, it is only 38 square feet of sail that squeeks through a tiny foretriangle area of a Catboat. I also made a Light Air Nylon Mainsail which really moves the boat in very light air when other boats are under bare poles using their iron Gennys! Remember in light to even moderate air Nylon is King!

Today I finished installing a bowsprit, bobstay, and whisker stays to have a platform to experiment with various headsails. Needed to increase that tiny foretriangle area!

capt_nemo

Nylon Drifter.




Light Air Nylon Mainsail, set flying.

[skip1930]

I don't know but maybe a resign impregnated molded fiberglass 20-1/2 oz woven cloth cap could be fashioned and molded to fit onto the CP-16's keel bottom and round out the flow instead of tolerating those pesky eddie currents that create drag. Like wheel pants for Cessna's 182's help gain a bit in speed and fuel economy. No keel cutting or other modifications necessary. Just raise the hull bunks on the trailer.

As for bridge supports this bridge in Sturgeon Bay sits on 80 foot long logs pounded into the mud...none of them ever hit rock when the bridge was assembled in 1930.

Still not sitting on rock the bridge has just undergone a refit for several hundred million...OUCH! If it was me I'd scarf the drawings and have BayShip Building fab up identical sections out of stainless steel angle, flat, and wide-flange beams. Build another bridge and have Rowen Salvage come in R&R the bridge sections, pound more logs and take the old sections out into Lake Michigan for burial at sea. Or scrap 'em.

Most of the fuss about the lead paint...bag, blast, vacuum, paint, not the right original color, bag, blast, vacuum, repaint. Geezzzz think we were made of $$'s.



skip.