Boat in build pics (2013 Fairline Squadron 78)

[rafiki_]

But you don't expect government to be joined up. You have the MCA and IMO wanting loud horns on bigger boats which they decide is >20m, and you have elf'n'safety wanting peace and quiet. They each faff about and get their own laws passed. And we're left with the conflict. Ah well...!

The main use of these horns will actually be to toot "thank you" blasts at the end of South of France firework displays Proper fog will be a once-every-5-years event

Sorry JFM, my mistake. I'd assumed they were to attract the attention of the nice ice-cream sales person, then when up close to get her to drop her 99's

 

[taz]

Sorry JFM, my mistake. I'd assumed they were to attract the attention of the nice ice-cream sales person, then when up close to get her to drop her 99's

Wrong hooters.

 

[MapisM]

Isn't the whole noise issue also related to the usage somehow, rather than just the dB generated by the horn?
I mean, even a car horn (whose noise is ridiculous in comparison), can become illegal if used for instance at night, constantly and with no reason, within a residential area.
I would guess that also for boats, most authorities would rather argue against an inappropriate usage, rather than the dB per se...

 

[Pennpromo]

Cowes Monte Carlo

I plan to put it on a ship to France mid June 2013 (there's no longer any rush for the cowes-MC race),[/QUOTE]

Looking very likely now that its back on: tremendous support from competitors, 27 have confirmed at the moment, finish looking more and more likely to be Monte Carlo. Start on the Thames, pits area at Wood Wharf in the shadow of Canary Wharf, where the super yachts moored up for the Olympics.
Hoping to announce more on Sat 12th at Excel.
You might have to change your plans ! SIMON.

 

[jfm]

OK, noted! My plans are flexible; it wont be booked n a ship till next March or something. Thing is, the Monaco finish then doubling back to Nice pretty much kills the thing for boat-based spectators anyhow. No chance of getting a private boat into Nice to be in the hustle and bustle apres race

 

[Pennpromo]

Finish Line

John, its by no means certain now that we will go back to Nice, we are working on a whole bunch of local contacts in Monaco to sort the finish line. Really hoping to announce more at the London Show. Do I sense that you could be up for doing the final leg? Lots of teams are looking to sell a seat for one or more! Sorry for the thread drift. Simon

 

[Bajansailor]

Another wonderful boatbuilding thread - thanks jfm.

Re the white caulking debate, here are a couple of photos of the deck of a Wally Tender that lives here - I think she is about 6 or 7 years old now, and is an older version of this Wally One : http://www.wally.com/one/

 

[Wandering Star]

Genuine question from me for a change, several people are using the term "handed" when describing the propulsion system, as in "a handed pair" - I've heard the term used before of course, but what does it mean?

Cheers, Brian.

 

[rafiki_]

Genuine question from me for a change, several people are using the term "handed" when describing the propulsion system, as in "a handed pair" - I've heard the term used before of course, but what does it mean?

Cheers, Brian.

One prop turns clockwise, the other counter clockwise, so the boat tracks true in a straight line. One of the gearboxes changes the direction, as clearly both engines spin the same way.

 

[Chiedozie]

wow the creation looks much artistic to me i liked this manufacturing of boat here. hats off to your invention.......

 

[rafiki_]

Isn't the whole noise issue also related to the usage somehow, rather than just the dB generated by the horn?
I mean, even a car horn (whose noise is ridiculous in comparison), can become illegal if used for instance at night, constantly and with no reason, within a residential area.
I would guess that also for boats, most authorities would rather argue against an inappropriate usage, rather than the dB per se...

With car horns they are tested and approved for sound levels as installed. Noise at night is about the nuisance level, not sound level.

 

[Piers]

Here's a picture (not a very good one, sorry) of the Kahlenberg horns installed. These are the business, with titanium diaphragm and powered by a compressor and air tank hidden behind the scenes. Supplied by Piers and Toby du Pre, posters on here, who own the European Kahlenberg distributorship, Kahlenberg UK. Those guys have been very helpful throughout with all the tech specs and control stations specs and are a delight to deal with. If you scroll down to the model D-330 here you can hear the horns

They're located on the GRP apron/roof above the lower helm windscreen and in front of the flybridge windscreen. You cannot put these on masts/radar arches on a 25m boat because they'd be too loud for people on the flybridge

Thanks for the plug, jfm!

I see there's been much comment on loudness, and thought the following may be of interest.

The minimum COLREGS requirements for loudness depends upon the vessel's loa, starting at 12m and immaterial whether for leisure, sail, motor, coded, commercial, etc, and are detailed here: http://www.kahlenberg.co.uk/imo-sound-signal-requirements

Local bye laws for harbours, rivers, lakes or inland waterways connected to the high seas, can demand alternative sound signals but have in the main to agree with the COLREGS.

How one handles crew having their ears damaged, depends on the skipper's briefing! My briefing is that if anyone is going to go fwd of the Pilot House, they should be aware the horns could be a tad loud...!

 

[Piers]

Here's a picture (not a very good one, sorry) of the Kahlenberg horns installed. These are the business, with titanium diaphragm and powered by a compressor and air tank hidden behind the scenes. Supplied by Piers and Toby du Pre, posters on here, who own the European Kahlenberg distributorship, Kahlenberg UK. Those guys have been very helpful throughout with all the tech specs and control stations specs and are a delight to deal with. If you scroll down to the model D-330 here you can hear the horns

They're located on the GRP apron/roof above the lower helm windscreen and in front of the flybridge windscreen. You cannot put these on masts/radar arches on a 25m boat because they'd be too loud for people on the flybridge

HI John,

Cleaning and keeping the horns polished is key to their long life. First, only use a chrome polish which has no abrasives. Stainless polish will wreck all chrome, so keep away from it. Only use a good non-abrasive chrome polish.

Then, use a carnuba wax, which from memory would be met by 3M's hard wax.

Finally, don't cover the horns. Using a cover creates a hot salty atmosphere not condusive to long life.

Have fun with the D330s.

Piers

 

[Cookee]

One prop turns clockwise, the other counter clockwise, so the boat tracks true in a straight line. One of the gearboxes changes the direction, as clearly both engines spin the same way.

In this case they do but: Richard Carr's race boat was designed with counter rotating engines so that everything was perfectly balanced, the boat is slim and capable of well over 100 mph, so any improvement in the balance would be an improvement in the handling of the boat.

 

[rafiki_]

In this case they do but: Richard Carr's race boat was designed with counter rotating engines so that everything was perfectly balanced, the boat is slim and capable of well over 100 mph, so any improvement in the balance would be an improvement in the handling of the boat.

There's always 1

 

[Cookee]

There's always 1

I'm sure it might be more common in the States but it's the first I've heard of racing in the UK - the boat is now back in the US racing.

Expensive way of gaining a small immeasurable amount of performance!

Sorry for the thread drift!

 

[rafiki_]

I'm sure it might be more common in the States but it's the first I've heard of racing in the UK - the boat is now back in the US racing.

Expensive way of gaining a small immeasurable amount of performance!

Sorry for the thread drift!

No need to apologise, as this is interesting info. There has been an epidemic of Fred Drift over the festive period, and forumites have been very tolerant

 

[MapisM]

I'm sure it might be more common in the States

Actually not so much, afaik.
Over the pond they tend to follow the principle that each engine has to be perfectly balanced in itself, rather than purposedly build a counter-rotating one.
Which btw is nowadays made even more difficult by the electronically-controlled-everything.
What they normally do on monohull vessels, is to place the engines staggered, to lower the CoG and fit the props as close as possible to the centerline.
And they often reverse the props - i.e. using a r/h prop on port side and l/h on stbd.
Apparently, surface props grab more solid water this way, and even if maneuverability can suffer, top speed is a notch higher.
Just curious, have you ever tried this on your boat?

With apologies also from my part for the drift, though I'm sure jfm doesn't mind a bit of technical drifting on his very technical thread...

 

[jfm]

Actually not so much, afaik.
Over the pond they tend to follow the principle that each engine has to be perfectly balanced in itself, rather than purposedly build a counter-rotating one.
Which btw is nowadays made even more difficult by the electronically-controlled-everything.
What they normally do on monohull vessels, is to place the engines staggered, to lower the CoG and fit the props as close as possible to the centerline.
And they often reverse the props - i.e. using a r/h prop on port side and l/h on stbd.
Apparently, surface props grab more solid water this way, and even if maneuverability can suffer, top speed is a notch higher.
Just curious, have you ever tried this on your boat?

With apologies also from my part for the drift, though I'm sure jfm doesn't mind a bit of technical drifting on his very technical thread...

I don't mind tech drift at all MapisM

I thought lots of race boats had inward turning props. The benefit of outward turning is mainly the exaggeration of turning effect when using one engine, which is very useful in the marina on a leisure boat. But if you don't care about that, then I understood inward turning makes sense in every other respect

As regards contra- or same- rotating crankshafts I'm curious about whether the gyro effect is significant. With contra engines everything is neutralised but if you have a pair of engines both turning same way then pitching of the hull in head seas should induce gyroscopic precession 90degrees away, ie a left/right steering effect that would have to be cured by rudders, = drag. My hunch would be that even at raceboat levels the effect of this is tiny* but I'd be interested to hear from Pennpromo/Cookee/others whether this factor is of interest to raceboat designers

* reason being (a) low crankshaft rpm in gyro terms eg 10,000 and of course even lower camshaft rpm, (b) small crankshaft radius + mass combined and tiny camshaft mass/radius; (c) absence of sustained periods of significant angular acceleration in the sort of seas a race would take place in; and (d) the length of a race boat makes its angular inertia higher (angular inertia of a spinning mass is proportional to square of its radius) and hence it is somewhat resistant to the turning effect of the gyro forces

 

[rafiki_]

I don't mind tech drift at all MapisM

I thought lots of race boats had inward turning props. The benefit of outward turning is mainly the exaggeration of turning effect when using one engine, which is very useful in the marina on a leisure boat. But if you don't care about that, then I understood inward turning makes sense in every other respect

As regards contra- or same- rotating crankshafts I'm curious about whether the gyro effect is significant. With contra engines everything is neutralised but if you have a pair of engines both turning same way then pitching of the hull in head seas should induce gyroscopic precession 90degrees away, ie a left/right steering effect that would have to be cured by rudders, = drag. My hunch would be that even at raceboat levels the effect of this is tiny* but I'd be interested to hear from Pennpromo/Cookee/others whether this factor is of interest to raceboat designers

* reason being (a) low crankshaft rpm in gyro terms eg 10,000 and of course even lower camshaft rpm, (b) small crankshaft radius + mass combined and tiny camshaft mass/radius; (c) absence of sustained periods of significant angular acceleration in the sort of seas a race would take place in; and (d) the length of a race boat makes its angular inertia higher (angular inertia of a spinning mass is proportional to square of its radius) and hence it is somewhat resistant to the turning effect of the gyro forces

Cricket JFM, this is quite heavy for a Thursday. Assuming the boat has an even number of engines, even if they are not counter rotating, there will be some cancelling forces around the longitudinal centreline of the boat, hence minimal procession?