Association Forum - More Weather Helm Theory

Assn Members Area · Join

Home.

Association Forum

Ships Store

Cruising

Racing

Technical Tips

Photo Gallery - New

Boat Search - Updated

Manuals & Brochures

Swap Meet

Links

Officer Flag Line & Staff

Bylaws & Constitution

Members Area

Join the Association

Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.

Association Forum

Username:	Password:
Save Password
Forgot your Password?

All Forums

Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

More Weather Helm Theory

New Topic

Topic Locked

Printer Friendly

Author

Topic

Page: of 3

Sea Trac
Master Marine Consultant

Members Avatar

Vanuatu
1357 Posts

Response Posted - 10/01/2003 : 19:20:33

Well, don't I feel smart? <img src=icon_smile_clown.gif border=0 align=middle> Just dumb luck, I'd actually been struggling just to keep up with all the engineering talk. Internet search engines are really an incredible tool. <img src=icon_smile_wink.gif border=0 align=middle>

So, what's construction foam?

J.B. Manley
Antares '85 FK/SR #4849
Grand Lake O' the Cherokees
36°29'58" -94°59'59"

Edited by - on

Arlyn Stewart
Master Marine Consultant

Members Avatar

USA
2980 Posts

Response Posted - 10/01/2003 : 20:30:02

Here is an example of some construction foam that came as dunnage with some thinner foam sheets that are used for wall sheathing.

<img src="http://www.stewartfam.net/arlyn/P0000298.JPG" border=0>

The use in the picture is for adding a skeg as the c250 has none. It was done to help solve a handling problem several years ago. Specifically, that problem was that the boat once into a hard turn... was very difficult to pull out which all but rendered the auto pilot useless as it couldn't overcome the rudder torque needed to get back on course.

Between adding the skeg and modifying the rudder head to rake the bottom of the rudder forward... the problem of getting out of turns was completely solved.

The foam was simply glued on with 3M spray adhesive and held on fine and remained looking good... remember, my boat doesn't stay in the water.

btw, the weird thing in the place of the rudder is the rudder head...inverted on the pintles for storage.

Arlyn C-250 W/B #224
<img src="http://www.cox-internet.com/arlynstewart/rr4.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.stewartfam.net/arlyn/"]Arlyn's C250 Mods n Cruising Stories[/url]

Edited by - on

Sea Trac
Master Marine Consultant

Members Avatar

Vanuatu
1357 Posts

Response Posted - 10/01/2003 : 22:14:31

Ya' know, Arlyn, Wild Bill Hickok got shot for havin' an ace up his sleeve. <img src=icon_smile_wink.gif border=0 align=middle>

J.B. Manley
Antares '85 FK/SR #4849
Grand Lake O' the Cherokees
36°29'58" -94°59'59"

Edited by - on

Dave Bristle
Master Marine Consultant

Members Avatar

Djibouti
10005 Posts

Response Posted - 10/01/2003 : 22:17:59

Hey Arlyn--I didn't know you had a C-25! <img src=icon_smile_cool.gif border=0 align=middle>

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette-Honda "Passage" in SW CT

Edited by - on

Sea Trac
Master Marine Consultant

Members Avatar

Vanuatu
1357 Posts

Response Posted - 10/01/2003 : 23:13:21

Not only that, but are my eyes tired or does that boat NOT have any kind of keel or centerboard?

J.B. Manley
Antares '85 FK/SR #4849
Grand Lake O' the Cherokees
36°29'58" -94°59'59"

Edited by - on

Arlyn Stewart
Master Marine Consultant

Members Avatar

USA
2980 Posts

Response Posted - 10/02/2003 : 05:40:56

Keel? Centerboard? Huh? Maybe thats the problem... <img src=icon_smile_sad.gif border=0 align=middle>

btw...ran into another theory to throw into the mix...
<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
*2 Heeling increases water line length on the lee side, causing the lee side to run faster than the weather side.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

http://www.naciente.com/sail6.htm

Arlyn C-250 W/B #224
<img src="http://www.cox-internet.com/arlynstewart/rr4.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.stewartfam.net/arlyn/"]Arlyn's C250 Mods n Cruising Stories[/url]

Edited by - arlyn stewart on 10/02/2003 06:16:24

Edited by - on

Frank Hopper
Past Commodore

Members Avatar

Pitcairn Island
6776 Posts

Response Posted - 10/02/2003 : 10:20:11

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
*2 Heeling increases water line length on the lee side, causing the lee side to run faster than the weather side.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
http://www.naciente.com/sail6.htm
Arlyn C-250 W/B #224
No wonder you need a skeg, no CB must would explain all the rudder experiments too.

He does not have that quite right. The boat is not sailing faster on the lee side, (relative to the ground). Bernoulli 101: The fluid flow is accelerated because nature abhors a vacuum and the molecules on the lee side must catch up with the paired molecule that were with them when the fluid split at the bow, the resulting spreading out of a constant number of molecules over a greater area produces lower density, hence the sucking that we call lift. On a hull we call it leeway. Nature likes stability and random acts of low pressure generate counter-acting forces to correct this. We exploit this to sail, (duh).

<img src="http://members.cox.net/fhopper/Catalina25/sigbow.jpg" border=0>Frank and Martha in Wichita KS. Lake Cheney

Edited by - on

Dave Bristle
Master Marine Consultant

Members Avatar

Djibouti
10005 Posts

Response Posted - 10/02/2003 : 11:53:47

Actually, that pic shows just one of Arlyn's two asymetric hulls, connected by a big trampoline... No boards required. <img src=icon_smile_cool.gif border=0 align=middle>

Now, to the longer waterline theory... Re-JECTed! Waterline length, relative to theoretical hull speed, is the length of the HULL at the waterline--not the side(s) of the hull. The hull LWL determines the speed at which the boat exceeds speed of a wave whose length, peak to peak is the distance from the bow wave to the stern wake of the boat. When it exceeds that speed, it has to climb up on the bow wave (semi-displacement) or leave it entirely behind (planing).

Nice try, however... <img src=icon_smile_evil.gif border=0 align=middle>

Note: It is possible to increase the LWL by heeling--particularly if you have a long overhangs (as on many classic designs).

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette-Honda "Passage" in SW CT

Edited by - dave bristle on 10/02/2003 11:57:21

Edited by - on

Page: of 3

Topic

New Topic

Topic Locked

Printer Friendly

Jump To:

Association Forum

Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.