Boat in build pics (2013 Fairline Squadron 78)

[MapisM]

I'm assuming now that you finally agree the rudders will be straight (and HDG 087)?

Ermm, nope, sorry.
I mean, I agree that the 87° heading with straight rudders would be the most efficient way to deal with such scenario (no wind, flat sea, engines perfectly synced - current being therefore the only variable affecting the COG), but I dont think that's what the a/p actually does, for all the above reasons/observations.

But rudder trim has nothing to do with cross currents. I disagree with you that one engine off is the "mother of all currents".
...

Point taken. I agree that "assimilating" the cruise on one engine to a strong current is not appropriate, but the point is that the a/p knows nothing of the reasons why the boat is either deviating from her heading, or COG, or both.
It just reacts, and I don't see any logical reasons why it should react differently to the effects of current vs. other effects, when he can't even understand the difference.

You seem stuck in a world where you think constant rudder (ie "trim") is needed to deal with a cross current. It isn't.

Oh, no, I understand that - see above: I also accept that "your" logic would be better, in the scenario which is being discussed.
I just don't think this is the way the a/p works.

 

[jfm]

On reflection, and now that I've woken up, I might have to give you this one!

Ah, fair enough, I did just check the time (0637am) you posted that

 

[jfm]

I just don't think this is the way the a/p works.

OK, then we should park the discussion for a few months or whatever, till we have more facts on a/pilot algorithms

 

[Cardo]

Here you go...

Much obliged.

 

[Elessar]

Is the complexity that the boat a/p needs to understand the reason that the boats track is different to heading? If wind, then rudder must be applied, if current, then a heading alteration is required?

nope. Still a sideways vector just like your diagram.

Despite all this ultimately all the a/p is doing in track mode is adjusting the heading if neccessary to make the COG correct, with "correct" having various amounts of complexity to smooth the course, but largely it is aiming to minimise XTE.

Note in all this that I'm struggling to read on a small screen, one of the factors taken into account by even basic a/p is boat speed, with rudder reaction angle inversely preoportional to speed. If it takes the data from STW (E3 did) it makes for a likely ride when the paddlewheel is stuck.

 

[petem]

nope. Still a sideways vector just like your diagram.

Despite all this ultimately all the a/p is doing in track mode is adjusting the heading if neccessary to make the COG correct, with "correct" having various amounts of complexity to smooth the course, but largely it is aiming to minimise XTE.

Note in all this that I'm struggling to read on a small screen, one of the factors taken into account by even basic a/p is boat speed, with rudder reaction angle inversely preoportional to speed. If it takes the data from STW (E3 did) it makes for a likely ride when the paddlewheel is stuck.

But it would have a choice to make pre-emptive or responsive corrections. Pre-emptive being to point the boat in the right direction (rudder straight ahem) then let current do its work or make small correction to rudder as it goes along?

 

[Pinnacle]

OK, then we should park the discussion for a few months or whatever, till we have more facts on a/pilot algorithms

Do you think MM could have had too much of the "amber nectar"?

 

[BartW]

The rams are double acting hydraulic but all the oilways are machined into the metalwork (including machined into the top pivot) with hoses only located inside the hull. This aspect is a properly clever bit of engineering and design by bennett and I'm not sure if any other ram maker is as clever on this score

there was one 20 years ago,
the rams on BA are similar like yours, (same nice method for the hydraulics in the pivot point)
we have been searching, but it seems they were custom made somewhere in Italy at that time.

looking from the inside of the transom:

The hydraulic pump is also Italian made,
and the indicaters “only” are bennett’s (confirmed by Bennett)

 

[jfm]

Is the complexity that the boat a/p needs to understand the reason that the boats track is different to heading? If wind, then rudder must be applied, if current, then a heading alteration is required?

I don't think so. For starters, perhaps the most common reason HDG differs from COG is bad set up, variation, and deviation caused by say somone putting a folding bike in a locker near the fluxgate

Furthermore, it doesn't have to be the case that a cross wind needs rudders; it depends on the boat/wind combo but it's at least possible that a cross wind can work somewhat like a cross current and needs an adjustment to HDG as well as or instead of rudders. As MM say, the a/p doesn't figure out why anything happens; it just reacts based on algorithms to the sentences it sees. We need to know more aobut the algorithms to go much further in this discussion.

 

[jfm]

there was one 20 years ago,
the rams on BA are similar like yours, (same nice method for the hydraulics in the pivot point) we have been searching, but it seems they were custom made somewhere in Italy at that time.

Hi Bart - that's interesting. Nice job. Actually I think a few makers have the hydraulic oilways totally inside the metalwork. Apart from Bennett, I think Phoenix might offer this. Do you need to buy new or are your current ones ok?

 

[BartW]

Do you need to buy new or are your current ones ok?

they are all ok,
but last year I had a leak in one,
the brass tube going through the transom in to the ram's base was slightly damaged.
We were able to repair this in Italy last winter , we fitted a new tube.

I have spend an hour or so, to clean that ram, so that it looked shiny ss,
but it has had new white antifouling,
I was considering to take the AF off next lift out, and leave the ss blank, just like the hilo system,

what are you going to do with your rams antifoul them or not ?

 

[jfm]

what are you going to do with your rams antifoul them or not ?

I think I will leave them as bare shiny s/s. Like the hi-lo - I will definitely leave the hi-lo unpainted because it was fine for 1.5 years like that on Match1 - on lift out there was some fouling but it came off with the jet wash

I like the unpainted look. I need to ask for some stickers on the rams saying "Do not paint" on my next visit to Fairline factory!

 

[Deleted User YDKXO]

Alternatively the a/p could calculate an alternative initial course (e.g 5 degrees) and set the oat in that sirection, then centre the rudder for the remainder of he journey. This would produce a very odd track and could only be done for a short journey.

Not nearly as dangerous as heading straight for the waypoint from the XTE position. If you think about it, the boat would never get back on track if the AP was only considering BTW. If any tide or wind was pushing it off track, it would constantly be at max XTE recalculating BTW all the time and if there was a rock within the XTE limit of the track, you'd be in danger

 

[jfm]

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

 

[jimmy_the_builder]

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

Very nice. What's the risk, if any, to people on the coachroof sunpad, or, ahem, enjoying a g&t in the sundowner chairs at the windlass?

Cheers
Jimmy

 

[jfm]

Very nice. What's the risk, if any, to people on the coachroof sunpad, or, ahem, enjoying a g&t in the sundowner chairs at the windlass?

Cheers
Jimmy

Perhaps Piers/ Toby will chip in but I'd say that apart from a month of profound deafness and a ruined shirt collar due the blood trickling down, nothing at all. I'll be switching it off at the isolator panel when I have my g+ts

 

[jimmy_the_builder]

Perhaps Piers/ Toby will chip in but I'd say that apart from a month of profound deafness and a ruined shirt collar due the blood trickling down, nothing at all. I'll be switching it off at the isolator panel when I have my g+ts

I was thinking of this moment (from Hurricane's recently-resurrected 'long cruise' thread)

Cheers
Jimmy

 

[jfm]

Ah yes, a very fine moment that, on a very nice cruise. Great photo. Yeah, the thought someone might accidentally put their iPhone down on the horn switch while they nip to the kahzee would really spoil your waah there on the foredeck. I'll definitely isolate it on the panel I think and mainly activate it to say thank you at the end of firework displays

Here's a zoomed out shot taken at almost the same moment

 

[rafiki_]

Perhaps Piers/ Toby will chip in but I'd say that apart from a month of profound deafness and a ruined shirt collar due the blood trickling down, nothing at all. I'll be switching it off at the isolator panel when I have my g+ts

Perhaps it will save you having to shake the Martini's

 

[prv]

You cannot put these on masts/radar arches on a 25m boat because they'd be too loud for people on the flybridge

Heh, indeed.

I sail occasionally on a square-rigged sail-training vessel, run like a commercial ship. The horns are on top of the bridge, but just in front of the bridge is an area of deck called the waist, where people tend to congregate. Every time they use the horn, they have to make a tannoy announcement first telling people to cover their ears

Pete