NormanS
Well-known member
Unless you eat beetroot.
Confessional: admit to boat-related things you've never quite understood...
- Thread starter dancrane
- Start date
Unless you eat beetroot.
maby
Well-known member
OK - here's one that is particulary relevant to me since I'm about to repeat it without knowing why!
Why do people bind up the bottle screws on their shrouds with tape? All our bottle screws are very carefully bound with white tape that is now beginning to fail and come undone - some time soon, i'm going to spend several minutes replacing it without actually understanding what it is there for!
Why do people bind up the bottle screws on their shrouds with tape? All our bottle screws are very carefully bound with white tape that is now beginning to fail and come undone - some time soon, i'm going to spend several minutes replacing it without actually understanding what it is there for!
dancrane
Well-known member
Isn't it like the coloured pointers attached to lorry wheel-nuts...they indicate if the nut has moved? The shroud attachments on my dinghy are likewise taped up...I've no idea why.
Uricanejack
Well-known member
10 pages on screws? Why don't they use robertsons. 
The tide is a vector it has force and direction or distance and direction.
As has the boat and the wind.
If the tide effect when thought of as a vector
When the tide is on the lee bow the vector acts towards the wind moving the boat into the wind increasing the apparent wind.
When the tide is on the windward bow the vector acts away from the wind reducing the apparent wind.
Think of it this way if there was no true wind at all. On a glass like sea.
At the same time there was a 2 knot tidal stream or current the boat would move down stream with the current through the air. You would feel the 2 knots of apparent wind. Opposite the current.
The sails would move through the air at 2 knots. Giving an apparent wind of 2 knots in the direction opposite to the current.
If you sheet in the sails they will catch the apparent wind and provide lift and move the boat forward.
Now the boat is under way it will move through the wind which will also increase the apparent wind.
Change to a regular day when there is wind.
You have the choice of two tacks. And a current in one direction.
If you chose to sail the tack with the wind and current on opposite sides the vectors will add together with the boats forward movement to increase the apparent wind.
When the tide turns tack.
If they are both on the same side the current will acting the same direction as the wind and reduce the apparent wind.
If the tide doesn’t change. You loos on the swings and gain on the round about.
It s all quite simple really.
Self tapping screws are for holding panels on washing machines and other kitchen appliances together .
So they will only fit together properly once in the factory.
Wood screws are for holding wood together when you can‘t be bothered to clamp and glue. It.
Bolts are for when you don’t want to use a rivet.
Studs are bolts which you screw in after you tap a drilled hole and intend to leave there and you put a nut ion the end of it. They are also a real pain when you over torque them and they break
As for what I don’t know I could fill encyclopaedias.
I used to know how to sell encyclopaedias. I wasn‘t very good at it though..
The tide is a vector it has force and direction or distance and direction.
As has the boat and the wind.
If the tide effect when thought of as a vector
When the tide is on the lee bow the vector acts towards the wind moving the boat into the wind increasing the apparent wind.
When the tide is on the windward bow the vector acts away from the wind reducing the apparent wind.
Think of it this way if there was no true wind at all. On a glass like sea.
At the same time there was a 2 knot tidal stream or current the boat would move down stream with the current through the air. You would feel the 2 knots of apparent wind. Opposite the current.
The sails would move through the air at 2 knots. Giving an apparent wind of 2 knots in the direction opposite to the current.
If you sheet in the sails they will catch the apparent wind and provide lift and move the boat forward.
Now the boat is under way it will move through the wind which will also increase the apparent wind.
Change to a regular day when there is wind.
You have the choice of two tacks. And a current in one direction.
If you chose to sail the tack with the wind and current on opposite sides the vectors will add together with the boats forward movement to increase the apparent wind.
When the tide turns tack.
If they are both on the same side the current will acting the same direction as the wind and reduce the apparent wind.
If the tide doesn’t change. You loos on the swings and gain on the round about.
It s all quite simple really.
Self tapping screws are for holding panels on washing machines and other kitchen appliances together .
So they will only fit together properly once in the factory.
Wood screws are for holding wood together when you can‘t be bothered to clamp and glue. It.
Bolts are for when you don’t want to use a rivet.
Studs are bolts which you screw in after you tap a drilled hole and intend to leave there and you put a nut ion the end of it. They are also a real pain when you over torque them and they break
As for what I don’t know I could fill encyclopaedias.
I used to know how to sell encyclopaedias. I wasn‘t very good at it though..
dancrane
Well-known member
10 pages on screws? Why don't they use Robertsons.
View attachment 37240
Excellent point...their jam-pot lids are screw-fittings, aren't they? But the jams aren't self-spreaders.
...a painted ship, Upon a painted ocean? I thought the lee bow was just something that performance-catamaran sailors try not to bury.
nigelmercier
RIP
- Joined
- 20 Jun 2007
- Messages
- 16,234
- Location
- Live in Kent, boat in Canary Islands
To prevent snagging on badly closed split-pins, and to promote corrosion.
Q: Is a snatch block a type of Femidon?
Last edited:
vyv_cox
Well-known member
No, I'm afraid it's more complicated than that, to do with whether water passes through the bypass or through the engine. Perfectly straightforward and comprehensible on Bukh and Yanmar engines but not Volvos. I will prepare a diagram later and post it as a new thread.
prv
Well-known member
Open body ones - to cover the split-pins so that they don't snag sails / clothes / skin.
Closed body ones - an attempt to seal the tommy-bar hole in the middle so that the body doesn't fill with water.
Pete
Uricanejack
Well-known member
View attachment 37240
Excellent point...their jam-pot lids are screw-fittings, aren't they? But the jams aren't self-spreaders.
...a painted ship, Upon a painted ocean? I thought the lee bow was just something that performance-catamaran sailors try not to bury.
One of those things about civilisation I really miss. But where the golly? Banned by the EEC?
Just won't taste the same without it.
dancrane
Well-known member
I wonder what they'll ban next? Marmite, perhaps...because the EEC won't want to encourage hatred, and Marmite seems to incite so much, they even use it as a selling-point.
Here's a sailing question for bargain-end yachtsmen...does any company anywhere still produce and sell salt-water soap?
Fossil
Member
The short answer to this is that there's a misleading aspect built into the question. The thermostat does nothing to control the water temperature. All it does when closed (ie when starting from cold) is to restrict the circulation of water around the engine block until the water already inside the engine has reached a predetermined temperature. This allows the engine to reach its best operating temperature faster. Once open, it allows cold water to be drawn in from outside and circulated around. The engine designer will have determined the size of the pipes and water pump necessary to ensure that when the engine is operating, the temperature it will reach remains within correct limits.
Roberto
Well-known member
Don't know but could your flask teach mine how to do it ? Whatever icy or boiling liquid I pour into it, 10 minutes later it's at ambient temperature
pete
Well-known member
Why is it that when someone posts a monster sized picture in a post I have to scroll back and forth to read all the text
nigelmercier
RIP
- Joined
- 20 Jun 2007
- Messages
- 16,234
- Location
- Live in Kent, boat in Canary Islands
Often not the "best", more of a compromise. I fitted a higher temperature thermostat in my original Mini and got a little more power out of it.
vyv_cox
Well-known member
Sorry, that is incorrect on several counts. The thermostat controls temperature regardless of the size of pipes and water pump. That's why they have the controlling temperature stamped into them.
However, your main error is to assume that all thermostats work as the ones in a car do. In Bukh and Yanmar raw water cooled engines the thermostat has a double function, allowing hot water out of the engine and simultaneously closing off the bypass. See separate thread, for which I am preparing some diagrams.
Meanwhile, look at this page http://www.asap-supplies.com/search/thermostat and compare the first two thermostats with the third.
john_morris_uk
Well-known member
If it's ignorance confession time I'm going to start another topic for discussion.
In Secondary Ports calculations, the Almanac gives you the time differences usually at 1200, 1800 etc for you to interpolate between to find the time difference for the secondary port you are interested in, based on the times of high and low water for the relevant primary port. Sometimes these time differences are negligible and sometimes they are appreciable. For the occasional secondary port where the minutes to add or subtract are large they are expressed as +131 or similar. I have never found anyone who can tell me whether that means one hour and thirty one minutes or one hundred and thirty one minutes!
This is slightly embarrassing as I teach and examine this stuff! However I remember asking a Hydrographer and he didn't know either so that makes me feel slightly better. Furthermore when I did my YM theory exam twenty five years ago, I asked the instructor and he mumbled something and changed the subject. Fortunately in real life, the requirement to use the figures for the very occasional secondary ports that give me this potential problem are so few that I've never found it a problem. I'd like to know the answer though...
In Secondary Ports calculations, the Almanac gives you the time differences usually at 1200, 1800 etc for you to interpolate between to find the time difference for the secondary port you are interested in, based on the times of high and low water for the relevant primary port. Sometimes these time differences are negligible and sometimes they are appreciable. For the occasional secondary port where the minutes to add or subtract are large they are expressed as +131 or similar. I have never found anyone who can tell me whether that means one hour and thirty one minutes or one hundred and thirty one minutes!
This is slightly embarrassing as I teach and examine this stuff! However I remember asking a Hydrographer and he didn't know either so that makes me feel slightly better. Furthermore when I did my YM theory exam twenty five years ago, I asked the instructor and he mumbled something and changed the subject. Fortunately in real life, the requirement to use the figures for the very occasional secondary ports that give me this potential problem are so few that I've never found it a problem. I'd like to know the answer though...
Simondjuk
Active member
The times are given in 24 hour notation, HHMM, thus 0113 = 1hour 13 minutes.
ditchcrawler
Well-known member
In Reeds as 1200 is 12hours 00mins and 1800 is 18hours 00mins the time difference would be expressed as 0131.I have always taken this as a difference of 1 hour and 31mins.AS you say some of the differences for the secondary ports are huge.Den Helder has a difference of -0520 for high and low water against the standard port of Helgoland.
I have roughly looked through the secondary ports in Reeds and cannot find a difference which is goes into the sixties or above e.g. 0162.
This leads me to believe that the differences are hours and minutes(I may be wrong of course)
I have roughly looked through the secondary ports in Reeds and cannot find a difference which is goes into the sixties or above e.g. 0162.
This leads me to believe that the differences are hours and minutes(I may be wrong of course)
Avocet
Well-known member
That's odd - they normally chuck out a few more horses if they run COLDER (as the air density going into the cylinders increases slightly).
john_morris_uk
Well-known member
Thanks and it appears that what I've assumed is correct. It's finding the definite answer that has foxed me so far and I always have a niggling doubt which in my OCD mind isn't helpful!