Captains,
Was aboard Hanalei this day, and repacked the thru hull valves. Always a fun time, but I thought I would post a hint on how to go at it easy.
First, if the thru hull valve is stuck, DON"T pound on it. You could bend the threaded part of the valve core. To free a stuck valve, first back off the lock nut and the adjusting nut. Remove them if you want, along with the limit washer if you can get it off. Then, take a 10" monkey wrench, size it to fit OVER the valve handle and the stud/web that the handle attaches to. This will keep you from breaking off the handle. You may be able to break it free by hand, but a light tap with a hammer(I use a short handled 5# sludge hammer) will free it instantly! Check to make sure that you are not trying to move the valve against the stop washer, not good, and you will waste your time.
Once the valve is out, wipe it off with kerosene, feel it, if smooth, don't bother going through all the lapping stuff, it just needs to be smooth, no groves. Grease it up with Morey's grease, reassemble, adjust and you are done.
I'll never struggle to get a stuck valve apart again.........I remain.......your most HUMBLE servant........
Dave Stump
Captain Commanding
s/v Hanalei CD-30C
CDSOA NUMBER ONE!!!!!
Repack your thru hulls......
Moderator: Jim Walsh
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Larry Austin
We removed our thru hulls,,,
,,,,fiberglassed in the holes for a nice smooth hull,,,,big race coming up,,,seeeeeeeeeeeeeeeeeeeeeeee ya!!
Larry Austin
CD30MKII
LAYLA
laustin@us.ibm.com
Larry Austin
CD30MKII
LAYLA
laustin@us.ibm.com
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D. Stump, Hanalei
Re: Pet a shark.............!!!!!!
Captain Commanding Layla,
Seriously, if you pet a shark, you will find that it is NOT smooth. Has very small bumps all over. Breaks the boundary layer of water to skin and makes that shark FAST!!!! Our nuclear submarines tried the same thing once, added a rubber layer that was textured, cut sound signal return and made the boat faster!!!!!!!!
Hanalei is NOT sanded smooth.........OH, almost forgot, kill shark before trying to pet it!!!!!!!!!!
Dave Stump
Captain Commanding
s/v Hanalei CD-30C
CDSOA NUMBER ONE!!!!!!!!!!
Seriously, if you pet a shark, you will find that it is NOT smooth. Has very small bumps all over. Breaks the boundary layer of water to skin and makes that shark FAST!!!! Our nuclear submarines tried the same thing once, added a rubber layer that was textured, cut sound signal return and made the boat faster!!!!!!!!
Hanalei is NOT sanded smooth.........OH, almost forgot, kill shark before trying to pet it!!!!!!!!!!
Dave Stump
Captain Commanding
s/v Hanalei CD-30C
CDSOA NUMBER ONE!!!!!!!!!!
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murray glue
Add more thru hulls then.
Thanks for the advice Capt. Stump. I am going to add another 20 or 30 thru hulls to Dayspring then, as soon as I get home.
murray@offshoretechnical.com
murray@offshoretechnical.com
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Michael Heintz
Re: Pet a shark.............!!!!!!
Captain Stump,
I will gladly take a ride up to your yard, and poke a few extra holes in you hull, rough it up a bit to test your theory...........
As too the shark....I ain't pettin no shark....dead or alive.......
Michael Heintz The real # 1 of the Northeast Fleet
Captain Cammanding
Macht Nichts
CD 30 MK II
I will gladly take a ride up to your yard, and poke a few extra holes in you hull, rough it up a bit to test your theory...........
As too the shark....I ain't pettin no shark....dead or alive.......
Michael Heintz The real # 1 of the Northeast Fleet
Captain Cammanding
Macht Nichts
CD 30 MK II
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Mark Yashinsky
Boundary Layer
Its also been tried in aircraft. Pinholes all over the wings connected to a vacuum source to srtip off the layer of air. Works too, except for other problems (ice, vacuum source, etc).
Hmmmm, now for the boat hull. Poke a ton of holes and suck the boundary layer of water in (to the boat). Need a test subject. Captain Stump???
Hmmmm, now for the boat hull. Poke a ton of holes and suck the boundary layer of water in (to the boat). Need a test subject. Captain Stump???
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Will W.
Re: Boundary Layer
I'm sure that most of this is in jest, but on a serious note. Don't the pro's take great pains to get a super smooth bottom ( on their boats)? I am not an expert and don't plan to be one but I am courious. Is it worth while to try to get as smooth a bottom as possible? Or does it not matter on a boat like a CD25?
Will Wheatley
Suzi Q
CD25
willwheatley@saterpower.net
Will Wheatley
Suzi Q
CD25
Mark Yashinsky wrote: Its also been tried in aircraft. Pinholes all over the wings connected to a vacuum source to srtip off the layer of air. Works too, except for other problems (ice, vacuum source, etc).
Hmmmm, now for the boat hull. Poke a ton of holes and suck the boundary layer of water in (to the boat). Need a test subject. Captain Stump???
willwheatley@saterpower.net
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D. Stump, Hanalei
Re: Is it worth it?????
Captain Wheatley
Maybe, if you had spent millions to win the America's Cup, but for our nice little cruisers, I doubt if you would notice the difference between a smooth bottom and a wrinkly one! Hum, did that come out right? I was talking about the vessels bottom, not your crews!!!!
Captain, Hanalei
Maybe, if you had spent millions to win the America's Cup, but for our nice little cruisers, I doubt if you would notice the difference between a smooth bottom and a wrinkly one! Hum, did that come out right? I was talking about the vessels bottom, not your crews!!!!
Captain, Hanalei
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John Nuttall
Laminar Flow, Boundary Layer and boat speed....
Ahhhhh here is a good topic.......challenging too....
I don't want to ruffle any feathers (even chicken feathers....;-] ) but things are just the opposite !!!!
The boundary layer needs to stay attached to the hull. Why? Well because the friction between the hull and H2O is greater than the friction between any two layers of water. The trick is how to get a layer of water to stay attached & how to keep it as thin as possible (thinner layers are less weight)
Now this phenom. occurrs naturally, and a good example is the Dolphin. They actually have little holes on their skin which create vorticies and turbulence. This turbulence keeps a thin layer of water attached to their bodies. As they slide thru the water with their hydrodynamic shape, the boundary layer stays attached, the laminar flow is maintained and drag is reduced. They go farther with less effort.
Golf ball dimples do the same thing - create turbulance at the surface to trap a layer against the ball. Sails too trap a boundary layer....
Racers sand their hulls down , but not much past 600 grit (I used to do this on my dry sailed Sonar). You need a little "tooth" to create slight turbulance to attach the boundary layer. Too smooth is actually slower because the layer keeps breaking away then reattaching, then breaking off again etc. This is slower, because of the increase in drag.
[If you really want to know what's up in this area check in with the guys at Finworks. They make fins for windsurfers and have been at the cutting edge of this stuff since the early 80s. They are light years ahead of "big boats" in this area, and I bet they can even teach a thing or two to even the designers if Americas cup boats.]
Now our thru hulls actually stick out thru the boundary layer and induce drag, so adding thru hulls is a no go ( Of course if some of the NE Fleet could convince "the pirate" this is a good idea, he might spend the summer doing it and well....).
Re the vacum trick on airplane wings. I'd guess that they were trying to recreate the same effect that's found on the skin of the Dolphins. I think that's called Han's Effect. ( I could check on that but I'd have to go out to the barn and get my Fluid Dynamics Text, it's out there in a place of honor in the same heap as my copy of the Theory of Relativity - LOL!)
Anyway, this is fun stuff to talk about and I'll try to find some links to sites about it...
John
s/v Aimless
CD31 #28
Hmpt: Oriental, NC
I don't want to ruffle any feathers (even chicken feathers....;-] ) but things are just the opposite !!!!
The boundary layer needs to stay attached to the hull. Why? Well because the friction between the hull and H2O is greater than the friction between any two layers of water. The trick is how to get a layer of water to stay attached & how to keep it as thin as possible (thinner layers are less weight)
Now this phenom. occurrs naturally, and a good example is the Dolphin. They actually have little holes on their skin which create vorticies and turbulence. This turbulence keeps a thin layer of water attached to their bodies. As they slide thru the water with their hydrodynamic shape, the boundary layer stays attached, the laminar flow is maintained and drag is reduced. They go farther with less effort.
Golf ball dimples do the same thing - create turbulance at the surface to trap a layer against the ball. Sails too trap a boundary layer....
Racers sand their hulls down , but not much past 600 grit (I used to do this on my dry sailed Sonar). You need a little "tooth" to create slight turbulance to attach the boundary layer. Too smooth is actually slower because the layer keeps breaking away then reattaching, then breaking off again etc. This is slower, because of the increase in drag.
[If you really want to know what's up in this area check in with the guys at Finworks. They make fins for windsurfers and have been at the cutting edge of this stuff since the early 80s. They are light years ahead of "big boats" in this area, and I bet they can even teach a thing or two to even the designers if Americas cup boats.]
Now our thru hulls actually stick out thru the boundary layer and induce drag, so adding thru hulls is a no go ( Of course if some of the NE Fleet could convince "the pirate" this is a good idea, he might spend the summer doing it and well....).
Re the vacum trick on airplane wings. I'd guess that they were trying to recreate the same effect that's found on the skin of the Dolphins. I think that's called Han's Effect. ( I could check on that but I'd have to go out to the barn and get my Fluid Dynamics Text, it's out there in a place of honor in the same heap as my copy of the Theory of Relativity - LOL!)
Anyway, this is fun stuff to talk about and I'll try to find some links to sites about it...
John
s/v Aimless
CD31 #28
Hmpt: Oriental, NC
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John Nuttall
An On-Line Course in Boundary Layer theory.... ;-}...
.....test to follow..LOL.....check out this link !!
John
John
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John Nuttall
More than you ever wanted to know about Boundary Layer Theor
.......a very stuffy paper, by some at Cambridge (UK).......
Might make a good substitute for Sominex...hehehe
John
Might make a good substitute for Sominex...hehehe
John
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John Nuttall
Even More Drek about Laminar Flow...With Pictures !!
......enjoy.......
John
ps- Term papers, 5 pages or less, are due by May 1st......
John
ps- Term papers, 5 pages or less, are due by May 1st......
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Will W.
Re: Even More Drek about Laminar Flow...With Pictures !!
Hi John
I will admit that the only reason I passed Physics was because my varsity football coach happened to be my teacher.
However after reading as much of this as I could (BTW I did fall asleep and had to pick up this morning)It seems that my question has been answered. Thank you for all the info, John.
Will
I will admit that the only reason I passed Physics was because my varsity football coach happened to be my teacher.
However after reading as much of this as I could (BTW I did fall asleep and had to pick up this morning)It seems that my question has been answered. Thank you for all the info, John.
Will
John Nuttall wrote: ......enjoy.......
John
ps- Term papers, 5 pages or less, are due by May 1st......
-
Hanalei
Re: My point exactly....
John,
Captain Nuttall,
You are correct, that IS more than I need to know, but, the reason the US Navy put that "shark" skin on a fast attack submarine was to break the laminar flow boundary layer (and quiet the boat, it was rubber if I remember right, and I never saw it, all rumor)) which would cut the power needed to drive the boat through the water - hence, a faster fast attack submarine!!! So, I would guess that if you could disturb the laminar flow layer on a CD's bottom, she would go faster, SOoooo, I don't hand sand the bottom on Hanalei, roll the paint on, and go sailing!!!! After all, Hanalei is already Sooooo fast that the entire fleet is trying to figure out how I do it!!!!
Hanalei
Captain Nuttall,
You are correct, that IS more than I need to know, but, the reason the US Navy put that "shark" skin on a fast attack submarine was to break the laminar flow boundary layer (and quiet the boat, it was rubber if I remember right, and I never saw it, all rumor)) which would cut the power needed to drive the boat through the water - hence, a faster fast attack submarine!!! So, I would guess that if you could disturb the laminar flow layer on a CD's bottom, she would go faster, SOoooo, I don't hand sand the bottom on Hanalei, roll the paint on, and go sailing!!!! After all, Hanalei is already Sooooo fast that the entire fleet is trying to figure out how I do it!!!!
Hanalei