Confessional: admit to boat-related things you've never quite understood...

[john_morris_uk]

The times are given in 24 hour notation, HHMM, thus 0113 = 1hour 13 minutes.

Thanks to you as well Simon.

 

[prv]

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!

I guess the thing to do would be to compare with a local tide table (either a specific printed one or as generated by a tide program - perhaps Admiralty Easytide as the source data is presumably the same). Work the Reeds calculation twice using the different interpretations, and see which one matches the local table.

Pete

 

[NormanS]

If you were cyclists you would know that the Apparent Wind is always in your face.

 

[Storyline]

Oh, and I had a question about anchors...

Hmm, One hundred posts in 21hrs, not too bad. It seems we all have doubts to confess (or guidance to give!)...

...I sometimes wonder about aluminium as a construction material...aren't owners of ally hulls afraid of envious folk attaching a bit of some superior metal, out of sight underwater?

Wouldn't the whole boat quietly degrade in reaction to the alien bit of steel?

I would be worried about dropping things such as coins that could find their way down into the bilge and slowly eat their way through.

 

[CreakyDecks]

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).

I think you are confusing ambient temperature and engine temperature. Look up Carnot cycle.

 

[laika]

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!

Have you tried mailing the question to tides -at- ukho.gov.uk? I believe they try and answer any tide-related questions that are put to them. (although prv's answer seems good)

 

[AntarcticPilot]

I would be worried about dropping things such as coins that could find their way down into the bilge and slowly eat their way through.

Mercury is the real no-no with Aluminium - it forms an amalgam and rots the aluminium very quickly. Even before mercury thermometers were generally taken out of use, they were banned on aircraft for exactly that reason.

 

[nimbusgb]

What about coach bolts ?

...I'll get my coat...

And left hand threaded prison screws.

 

[Storyline]

Mercury is the real no-no with Aluminium - it forms an amalgam and rots the aluminium very quickly. Even before mercury thermometers were generally taken out of use, they were banned on aircraft for exactly that reason.

I presume the Ovnis and such have some kind of coating internally on their bilges.

 

[Easticks28]

.....racing types who, the slower they go, the louder they shout....

 

[TonyBuckley]

Thank you to those that have helped explain the difference between True and Apparant wind. I have read the wiki, looked at the vector formulas and understand what is being said.

But... I still don't understand why the heck I should care? Or need to know about this. It must be important as there is a button on my wind instrument to switch between the two.

Surely we all trim our sails as we sail. Adjusting to the wind conditions as they really change or seem to change.

My boat max speed is about seven knots and I could just about understand why tacking for example could change things but I seem to have managed this quite well without pushing buttons on instruments or doing vector equations.

Still confused

 

[Woodlouse]

Thank you to those that have helped explain the difference between True and Apparant wind. I have read the wiki, looked at the vector formulas and understand what is being said.

But... I still don't understand why the heck I should care? Or need to know about this. It must be important as there is a button on my wind instrument to switch between the two.

Surely we all trim our sails as we sail. Adjusting to the wind conditions as they really change or seem to change.

My boat max speed is about seven knots and I could just about understand why tacking for example could change things but I seem to have managed this quite well without pushing buttons on instruments or doing vector equations.

Still confused

When sailing, keep your instruments set to apparent wind since that is what the sails are experiencing so that is what you steer and trim to. Switch it to true wind so you can find out how windy it actually is for bragging rights in the pub, otherwise it's uses are limited when sailing.

 

[alant]

Maximum beam of the hull is not at deck level, but lower down. So looks fat from ahead or astern. Partly driven by rating rules and partly by (IMHO misplaced) aesthetics. Very popular with some designers about 40 or more years ago!

+ Nelson.

 

[alant]

...please don't bother posting if you think you know it all.

Here's one to get the ball rolling, which often occurs to me whilst at the boat, although the question isn't actually a sailing one.

What the hell does self-tapping mean? Every how-to video or description of equipment-assembly seems to use 'self-tapping' screws/bolts. What does it mean?

The one that puzzled me when I first heard it, was 'bifurcated rivet'!

 

[Woodlouse]

Talking of rivets, can anyone tell me exactly where the golden one is on a boat?

 

[alant]

If you were cyclists you would know that the Apparent Wind is always in your face.

Does that mean Apparent Wind, is a red bus?

 

[alant]

Mercury is the real no-no with Aluminium - it forms an amalgam and rots the aluminium very quickly. Even before mercury thermometers were generally taken out of use, they were banned on aircraft for exactly that reason.

Anything caustic works well, forming aluminates.

 

[alant]

Talking of rivets, can anyone tell me exactly where the golden one is on a boat?

You can see it if you bend over.

 

[prv]

Switch it to true wind so you can find out how windy it actually is for bragging rights in the pub, otherwise it's uses are limited when sailing.

Main use of true wind is when motoring due to lack of breeze, but hoping it will fill in enough to be able to sail. The apparent wind from moving forward keeps tempting you into thinking that you'd be able to sail; the true wind display tells you whether there really is.

Personally I wish I could set my ST60 to display apparent wind direction with the dial, but true wind speed in the LCD window. I rarely care about the true wind direction or the apparent wind speed; without this mode I'm always flicking back and forth.

Pete

 

[macnorton]

As some one else said alternators & there wiring and engine wiring looms generally...

Look up "flemings right hand rule" for alternators.
Think of the plumbing in your house for wiring.