Keel or "Through Hull" cooling?
- Thread starter PaulJS
- Start date
Brent Swain
N/A
Compared to the vast wealth of experience based info you have provided on the subject?
Took you over 5 years to think up that reply, glad it wasn't a pressing question!
pvb
Well-known member
What on earth is the point in replying to a thread which died over 5 years ago?
pete
Well-known member
Well I found it interesting thanks even if you didn't, are we running out of space on this forum or something ?
Brent Swain
N/A
Took you over 5 years to think up that reply, glad it wasn't a pressing question!
When one compares the number of people on a forum to the number of people posting, you realize that most are just seeking info rather than giving it. Thus the number of new posts , or how long its been since a new one was posted, says nothing about how actively it is being used.
So, if one has new info which was not posted in the original discussion, then why should those seeking info on any subject have to weed thru a lot of similar threads, for the same info. Simpler to just add to what has already been posted.
I post just to pass on what I have learned in over 40 years of boat building, mostly full time cruising , living board , and building and designing steel boats.
Rolling of the eyes is an admission you have no real, valid, counter comments to make. Its a sarcastic "chicken out" from a valid debate.
pvb
Well-known member
I'm certainly not chickening out from a valid debate at all. I see no useful purpose in responding to a thread which finished and died many years ago, especially as many of the posters are probably no longer active on these forums. What's even worse - and I guess is the core of my objection - is that it's not terribly obvious from the forum software that it is a dead thread. As a result, people jump in and respond to early posts in the dead thread, without looking at the dates those posts were made. It would make much more sense, if someone genuinely does have new information on a topic, to start a new thread and to reference the dead thread with a link so that people can read the dead thread if they're so minded.
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PaulJS
Well-known member
Anyway, as the OP, and just to throw a little fuel on the fire with a pertinent update... Our brand new, glass fibre, displacement hulled, 30hp diesel powered rescue boat, which is designed to do about 6 knots and is about 7 metres long, has a dry exhaust and a keel cooler. The exhaust exits above the water line through a simple flap and the keel cooler is a single 2 meter, 1-1/2 inch bronze or copper tube. The sea water temperature here is about 35°C and it seems to run cool enough even when operated by a Chief Mate who thinks that a Morse control lever has only 3 positions - full ahead, full astern, and stop! The exhaust is noisier than my ancient sea water injected BMC diesels, but not much.
I guess that there are pros and cons for both systems, and I agree that keel cooling and dry exhausts need to be designed into the original specifications, but despite some of the responses from five years ago, I still think that keel cooling is better engineering solution if only for reducing the risks caused by the reliance on bringing sea water into the boat for cooling purposes.
So, I'll watch out for further contributions in 2022...
I guess that there are pros and cons for both systems, and I agree that keel cooling and dry exhausts need to be designed into the original specifications, but despite some of the responses from five years ago, I still think that keel cooling is better engineering solution if only for reducing the risks caused by the reliance on bringing sea water into the boat for cooling purposes.
So, I'll watch out for further contributions in 2022...
Brent Swain
N/A
A friend circumnavigated on one of my 36 footers with a raw water cooled, Yanmar 2GM 20. No problem, he swore by it. After 7 years on her, he sold the boat ,and several days later, the head cracked. When I asked mechanics about the problems with raw water cooling, they all said
"It works great for 7 years then the head cracks."
As all the hull surface on a metal hull is cooling surface ,it makes no sense to not go keel cooling on any metal hull.
Retrofitting dry exhaust on an existing boat was no problem for friends who have done it.
"It works great for 7 years then the head cracks."
As all the hull surface on a metal hull is cooling surface ,it makes no sense to not go keel cooling on any metal hull.
Retrofitting dry exhaust on an existing boat was no problem for friends who have done it.
Oi! I *like* my raw-water-cooled 2GM20
In particular, you really need a metal hull, so that the cooling tank can be integral - running pipes along the outside of a wooden or GRP hull, though I've seen it done, always looks vulnerable to damage and fouling, and adds drag.
You'd also need to design the layout with the exhaust stack in mind - retro-fitting it to a typical boat would involve a lot of unsightly boxing-in of hot components, and you probably couldn't follow the route that the original hose did.
Pete
prv
Well-known member
Somewhat different needs for a lifeboat. For one thing, it lets you start the engine while still hanging from the falls, without destroying a raw-water impeller or burning a rubber exhaust. Not something I've ever missed in relation to a yacht
Pete
PaulJS
Well-known member
Somewhat different needs for a lifeboat. For one thing, it lets you start the engine while still hanging from the falls, without destroying a raw-water impeller or burning a rubber exhaust. Not something I've ever missed in relation to a yacht
Pete
Very true Pete, but from a different viewpoint it might be useful to have the ability to run your engine for a few minutes when not in the water, and I was really trying to point out that a rescue boat (not a lifeboat) with similar size, power, and speed to many yachts uses keel cooling, presumably the manufacturer thinks it a better system.
Brent Swain
N/A
I use skegs for cooling. Many traditional boats with rudder too far forward, can be drastically improved by adding a skeg and transom hung rudder, much further aft. I have done something similar on my first boat, a huge improvement. That allows you to use a much simpler wind vane and inside steering, but also allows you to plumb the skeg for engine cooling, if you use a steel skeg.
Brent Swain
N/A
A friend had a bit of rust in his keel cooler, despite the use of antifreeze as an anti corrosive, until he put a bit of water soluable machinist's oil in. After that, the surface just looked oily ,no further corrosion.
Doesn't take much oil.
doris1914
New member
In answer to PVB above. Really?
I was hunting for info on keel cooling and ran across this thread, I enjoyed reading it and now have some more things to think about regarding keel cooling our classic yacht. I often read old posts on forums and frequently post a comment if I feel a need someone else like me may find it helpful. Now I need to track down Brent's book and learn some more, when I make my decision and get the cooling set up I will let people know how it went and what I learned along the way.
Cheers Andrew
I was hunting for info on keel cooling and ran across this thread, I enjoyed reading it and now have some more things to think about regarding keel cooling our classic yacht. I often read old posts on forums and frequently post a comment if I feel a need someone else like me may find it helpful. Now I need to track down Brent's book and learn some more, when I make my decision and get the cooling set up I will let people know how it went and what I learned along the way.
Cheers Andrew
TLouth7
Active member
No no no, you were supposed to wait until 2022
So, I'll watch out for further contributions in 2022...
rogerthebodger
Well-known member
I wouldn't bother with brents book as some of his ideas are quite off the wall.
I have a steel boat and considered keel cooling my engine but that then needs some separate cooling of lagging the engine exhaust.
You also need some raw water for other items like heads etc.
I went for conventional engine cooling. I did use the skeg as a form of keel cooling for my air conditioning system and fridge/freezer.
rob2
Active member
As others have already said, it is worth considering at the design stage but would rarely be worthwhile as a retrofit.
Another consideration is the very nature of diesels in a sailing yacht. They actually have quite a hard life from lack of use. It is most commendable that so many last for several decades often without the regular maintenance advised by the manufacturers. Many owners take the attitude of "If it ain't broke don't fix it." A well thought out installation, particularly including considering its height relative to water level, will last way beyond its components' design life. BUT the common power train and exhaust systems are flexible in application so that the installation doesn't have to be bespoke to each individual boat's design. The engine manufacturers are a bit coy when it comes to life expectancy of their products, but none would suggest more than 20 years I guess. That leaves a bespoke keel cooler and dry exhaust as something of a wasted expense when the new engine doesn't match up (and new models never do).
I well remember changing a friends two-stroke engine for a diesel. The existing exhaust could have been modified to suit with its dry system, but the welder advised us to go wet unless we wanted to see him more often than he saw his family.
Rob.
Another consideration is the very nature of diesels in a sailing yacht. They actually have quite a hard life from lack of use. It is most commendable that so many last for several decades often without the regular maintenance advised by the manufacturers. Many owners take the attitude of "If it ain't broke don't fix it." A well thought out installation, particularly including considering its height relative to water level, will last way beyond its components' design life. BUT the common power train and exhaust systems are flexible in application so that the installation doesn't have to be bespoke to each individual boat's design. The engine manufacturers are a bit coy when it comes to life expectancy of their products, but none would suggest more than 20 years I guess. That leaves a bespoke keel cooler and dry exhaust as something of a wasted expense when the new engine doesn't match up (and new models never do).
I well remember changing a friends two-stroke engine for a diesel. The existing exhaust could have been modified to suit with its dry system, but the welder advised us to go wet unless we wanted to see him more often than he saw his family.
Rob.
doris1914
New member
Well one thing I have most certainly learned from browsing forums is that there is a vast diaspora of people in any given community of a forum, I have also learned that far too many people are very quick to knock other people's thoughts and ideas, and often based only on assumptions rather than knowledge of the other party involved. No one designe is perfect and no one system is the best solution for every situation.
As it happens we are busy getting a 105 year old Dunkirk little ship in a fit state to be relaunched, She is a beautiful wooden hulled 78' twin screw motor yacht. Her twin Gardner engines are now 50 years old (installed into the boat in
As it happens we are busy getting a 105 year old Dunkirk little ship in a fit state to be relaunched, She is a beautiful wooden hulled 78' twin screw motor yacht. Her twin Gardner engines are now 50 years old (installed into the boat in
Rappey
Well-known member
Really? People google a boat related query. Lots of links to this forum turn up... Now you could find this forum is the only place with the info you are looking for, but its 12 years old.. A little dissapointing maybe?
Sometimes the info has been added to (like this thread) technology has moved on and sources for information have increased dramatically leading to a possible whole new angle on what was once a redundant thread.
pvb
Well-known member
I posted that comment over 2 years ago. Have you taken that long to think up your reply?
Dead threads keep being resurrected in these forums. It would be far better if people just started new threads with their questions.
