Re engine 16M trawler yacht

[jimmy_the_builder]

Hi Jimmy,
I don't know whether you've seen a Targa 40 with a letter box passerelle in operation. But as I understand it from a fabricator that asked to look at mine to check feasibility of fitting one on the port side for a client.

Fairline only supplied two T40s' with passerelle. The scope was very limited, in terms of length due to the locker being short and too shallow for three sections. This also meant a limited arc and raising angle. The other annoying point I was told was that the pump was too small and it took about a minute to extend just 5 feet.

If this is the case then I think you made the right choice. How would you have felt if you had spent £7K for something to wind you up even tighter.:encouragement:

Roger.

Hi Roger, no, never seen one working in the flesh. I didn't know the number supplied by Fairline was so small, tbh I'm surprised at that because I've definitely seen more than two with the option in the wild - maybe they are retro's? The OE unit was a Besenzoni, a PI374 Onda iirc, and you're right, it didn't extend very far - but it was just far enough to get you over the bathing platform and up to the quay. I didn't know that about the pump though - that would deffo be v annoying.

What I need, and have tried (and failed) to design, is a bigger bathing platform for the T40, with a clever two-way mechanism where the platform can lower a bit into the sea for that beer-on-a-directors-chair-toes-in-the-water experience, but also rise up maybe 500mm so you step _up_ from the companionway on the boat to the platform, and then it's just a small step up again to the quay. A bit like that Opacmare Transformer you see on the back of the big Ferretti's, only on a titchy scale.

 

[Whopper]

Lead ingots, made in small bread-making tins. They are sprayed in gold paint and so when you lift the floor hatches it looks like SilverDee is smuggling about 20million quid's worth of gold ingots

And what is the current weight roughly? If it's a case of; there are occasions when you want ballast and occasions when you don't, would water tanks fillable by pump be suitable? I know lead is probably better but from my experience from wakeboard/ski boats, built in fillable ballast tanks are pretty effective. Granted I only take on 1000l or water!

 

[MapisM]

maybe “the panel” can offer opinions on the following....

LOL, are you sure to want to get us started on all that?!?
If there's one thing I can tell you for sure, it's that after all the views you can get around here, you will eventually be more confused than ever...
Mind, not that I don't want to give also my contribution to the confusion, but it'll revert asap, 'cause right now I don't have time enough to answer your questions as they deserve.

Just one comment for the moment, re...

like anyone would, we do our bit to help the RNLI but we don’t profess to be as tough as those guys and girls

While on one hand I'm not so sure that ANYONE would have done what you did, I'm pretty sure that in the boots of that lost diver I would have been extremely happy to see SD approaching before darkness, no matter how badly she was rolling and whether her crew had a RNLI uniform or not.
Chapeau.

 

[MapisM]

Except that the 'increase' (above) is back to front. More ballast, lowers the C of G. Lowering increases stability but decreasing the role period

RR, I'm afraid the original jfm version (lower ballast=higher moment of inertia=longer roll period) was correct.
But I can't expand further, as I'm logging off now for some sleep (very early flight tomorrow).
Now, why do I see yet another armchair naval engineering debate at the horizon...?

 

[westernman]

I’ve also attached a bit of detail on the 6068AFM John Deeres that we’ve settled on (just need to wait the 3 months now)

Can you tell us why you picked that particular engine?

 

[RogerRat]

RR, I'm afraid the original jfm version (lower ballast=higher moment of inertia=longer roll period) was correct.
But I can't expand further, as I'm logging off now for some sleep (very early flight tomorrow).
Now, why do I see yet another armchair naval engineering debate at the horizon...?

Don't think so..."lower ballast=higher moment of inertia" True but 'higher', in this case means 'bigger' moment not 'higher' as in altitude. This means that the roll period is reduced as the righting moment is increased and therefore roll period shortened. Well at least that's the way I understand it. The aim is to lengthen the time of roll from side to side. Increased ballast would decrease it.

 

[jfm]

Don't think so..."lower ballast=higher moment of inertia" True but 'higher', in this case means 'bigger' moment not 'higher' as in altitude. This means that the roll period is reduced as the righting moment is increased and therefore roll period shortened. Well at least that's the way I understand it. The aim is to lengthen the time of roll from side to side. Increased ballast would decrease it.

Roger that isn't right. Adding ballast (say the keel bulb on a yacht) increases the righting force but not the speed at which the hull will rotate to an upright position. It actually decreases the speed, ie increases the roll period

Think of pendulum on grandfather clock. If you slide the weight downwards, you haven't changed the kg but you slow down the oscillation. In other words you increase the roll period. If instead you leave the weight at the same height, but you double its kg by making it from lead (say) you also slow the oscillation down, ie the extra weight increases the roll period. The extra weight of course creates a greater torque about the pendulum's shaft as the pendulum swings, but it swings more slowly

Thus, adding ballast or keel weight to a yacht creates a stronger force to resist the wind tipping the boat over, but it increases the roll period (ie slows down the oscillation)

If you go back to your Princess 98 ship load, the captain couldn't care less about a capsize as he wouldn't be exposed to that. (He would have had the calcs done of course!) He cared about slow rolling so that the acceleration forces on all the straps holding his cargo were smaller and his cargo wasn't jerked around. To achieve that, he wants the heavy princess 98 high on the deck, not low down in the hold, exactly as you said in the Princess 98 post

 

[MapisM]

Soooo... Back to SD questions

MapisM – the throttles have been like that since I had the boat….

I see. Actually, my previous question was not just related to the lever position, but also because that type of throttle is normally used in a dual lever configuration, i.e. with two levers for each engine, one for the shift and the other for the throttle, while in yours (aside from the small stick on the left side of each box, which I don’t know what’s there for) it looks like you've got two single levers, i.e. one lever for each engine, controlling both the shift and the throttle.
Not that it matters anyway, I’m actually a fan of the “if it works, don’t fix” it principle, and I also agree that on a boat like yours (and the very same goes for mine, btw) there’s no need to play with both throttles with one hand!
Re. replicating the thrusters controls in the cockpit for Med mooring, actually I’d rather have only the throttles (which give you both a full longitudinal control and a bit of sideways control) than the thrusters alone (which only give you the sideways control).
In fact, when mooring stern to in crosswind, there’s a basic trick that makes any thruster redundant: just secure the upwind stern line PDQ, and engage the downwind engine in fwd, just at idle. This way, you will be able to keep the bow from drifting downwind even more effectively than with a b/t, giving your crew all the time they need to recover and secure the bow line.
Which incidentally is at risk of getting tangled in the b/t while it’s being pulled onboard, if it gets anywhere near the b/t while it’s spinning.

before she had the ballast she would literally blow over in strong winds to an uncomfortable angle and then you had to go and shut the fuel stops on whichever side tank was upwind to stop it draining through the keel tank to the other side and accentuating the angle further.

Do you mean that you don’t have any valves along the hoses which connect the tanks? That’s weird...

1. Air Conditioning.
…
their real suggestion rather than buying new units was that I’d try and get those working and they could be re-gassed if necessary and sorted out fairly cheaply. Do people think I am mad going down that route

Nope, I for one don’t think you’re mad. A/C is imho overrated. In the Med, you want to spend your daytime outside anyway, so the potential problem with hot weather is only at night. Personally, I practically NEVER had to turn the A/C on while overnighting at anchor, and in a marina I turn it on maybe 4 to 6 days each summer. Ok, make it 8-10 days this year, 'cause we had more hot and windless nights than usual. Of course, all that depends also on how well the air circulates in the cabins, and how well the boat is insulated.
Which might be a critical point in a steel boat, I reckon.

2. Passerelle. To be honest, I’m thinking of going for an old fashioned one with the rope and pulleys type job instead of hydraulic.

Well, people have gone boating in the Med for decades with no hydr passerelle, also on some pretty big and luxurious boats, so you surely can go that route.
But you don’t have davits astern, or do you? The typical manual passerelle setup is with ropes and pulleys maneuverable through some sort of manual davits. Which of course are much less expensive than an hydraulic passerelle, and can also be used to hold a small rib while cruising, but all considered I’d rather bite the bullet and go for a hydraulic passerelle.
Fwiw, I had the stern davits and a manual passerelle on my boat when I bought her in 2000, and the replacement with an hydraulic passerelle is one of the first upgrades I made - and I’m glad I did.
Btw, it has worked flawlessly for more than a decade now (and counting, touch wood), so the reliability ain’t too bad, if you choose the right supplier and install them properly.

3. The vexed topic of marine loos. My 4 all use sea water…

My personal view on this is rather radical: I just hate seawater loos. Maybe it was a matter of materials/installation/brand/whatever (considering also the replies of other folks who don’t see anything wrong with them), but my personal experience is that when I bought my boat she was only 4 years old and the original seawater WCs were smelly, rusty and noisy. I almost immediately threw them away, installed Tecmas, and had them connected to the fresh water circuit.
Bottom line, they are now 3 times older than the original WCs were when I replaced them, and aside from a slightly yellowed cover, they look and work exactly as they did when new. Another league, really.

4. Tek-deck or similar.
…
do people think it is worth the money?

Short answer, no.
Mind, I have teak everywhere on decks, but in a wooden boat that comes with the territory. If I had either a GRP or a steel boat, I wouldn’t want to cover the decks with yet another maintenance-demanding bit of kit.
Yes, it looks nice. And yes, it feels better than anything else when walking barefoot onboard (aside from when it get real hot, and indeed it does, at times). But these pros alone don’t justify it, imho.

5. Bimini.
…
What are the views, fixed versus fold up? A hard top would be nice but I’m not minded to spend the money, but again opinions always welcome.

There are pros and cons for each solution of course, no right or wrong here.
I went through the very same evaluations just a few years ago, and eventually made a sort of semi-hard top, which can also be lowered for covering the whole f/b when it's not used.
Far from pretending that it’s the best solution - as I said each alternative has its pros and cons.
But so far it proved to work very well for my boat, and in hindsight my only regret is that I should have done it earlier.
If you wish to have a look, the initial ideas for the job were debated in the following thread:
http://www.ybw.com/forums/showthread.php?228379
And the final result was presented and discussed here:
http://www.ybw.com/forums/showthread.php?275526

Good luck for all these projects, and keep us posted.
It looks like you have enough irons in the fire to feed the forum for the foreseeable future!

 

[MapisM]

Don't think so..."lower ballast=higher moment of inertia" True but 'higher', in this case means 'bigger' moment not 'higher' as in altitude.

Yep, that's what I meant, but with the opposite conclusion in terms of rolling.
Aside from the latest further explanations jfm gave, I would add that you are possibly mixing the dynamic stability with the angular momentum, while they are instead separate concepts.
With a lower ballast, both increase, AOTBE, but that's incidental. The fact that the latter increases, that's what drive the longer roll period.

That said, I wouldn't be as radical as jfm was in suggesting that SD would perform better overall just by chunking the ballast overboard.
There are many effects involved, and it's difficult to estimate each pros and cons.
Btw, the fact that SD is thinking to fit a hardtop over the f/b could change the boat behaviour slightly, in this respect.
Maybe a seatrial with the crew busy moving the gold ballast all over the place could be a way to find out the best combination...?

 

[jfm]

SD, my 2p worth on a few of those:

1. A/C yes see if you can get it going with a re-gas or something. If that doesn't work out no big deal and you can do further things only if you need to. I agree with MapisM
2. Passerelle - hydraulic is very nice but I see no problem at all trying out something simpler for the first season. Just dont spend too much, because you will likely switch to hydraulic at some point, maybe in year 2. Remember a passerelle needs to be sturdy - you're fine, but helpers, guests, etc (me!) will like something sturdy. A nice hydraulic job is around £7k fitted
3. I'm with MapisM - freshwater loos. And Tecma next time you upgrade. But that's a preference - seawater will of course work and you have more important tasks to think about.
4. Decking - all down to personal choice. Teak or fake teak certainly looks nice, imho. I have mailed you some samples of fake teak to ponder over
5. Bimini - I like the idea very much of a fixed bimini, as fitted to MapisM's Azzura trawler yacht - see his link. But the trick in getting this right is to use thick tube (rough guess: the has used plenty of 40mm dia, with only limited use of 30, and no 25mm?) AND to get the edge detailing right. See how MapisM's has double tube all around the edge, then the canvas folds over to form an "upside down tray". That is the proper way to do it; you see that on a lot of big US centre console boats. All that said, the fixed bimini will surely be waaaay more expensive than a simple pram hood folding bimini. So if you want to get something ok but minimise cost in year 1, then get a simple series of goal posts bent in 30mm tube, fit catalogue end fittings from www.seascrew.com or baseline marine or asapsuppplies, and make a simple pattern for a covermaker to make the canvas part. Should be £1k max, all in

 

[RogerRat]

Roger that isn't right. Adding ballast (say the keel bulb on a yacht) increases the righting force but not the speed at which the hull will rotate to an upright position. It actually decreases the speed, ie increases the roll period

Think of pendulum on grandfather clock. If you slide the weight downwards, you haven't changed the kg but you slow down the oscillation. In other words you increase the roll period. If instead you leave the weight at the same height, but you double its kg by making it from lead (say) you also slow the oscillation down, ie the extra weight increases the roll period. The extra weight of course creates a greater torque about the pendulum's shaft as the pendulum swings, but it swings more slowly

Thus, adding ballast or keel weight to a yacht creates a stronger force to resist the wind tipping the boat over, but it increases the roll period (ie slows down the oscillation)

If you go back to your Princess 98 ship load, the captain couldn't care less about a capsize as he wouldn't be exposed to that. (He would have had the calcs done of course!) He cared about slow rolling so that the acceleration forces on all the straps holding his cargo were smaller and his cargo wasn't jerked around. To achieve that, he wants the heavy princess 98 high on the deck, not low down in the hold, exactly as you said in the Princess 98 post

Love it JFM, and your analogy of the pendulum.

Hey, don't get me wrong I'm no expert and don't profess to be one, but my understanding of roll period was arse about face as the idea in the P98 thread was to do the opposite of the increased weight in the clock's pendulum to reduce the righting moment.

It's more like the Mechanical metronome, raise the weight and roll period extends (slows down by raising the 'GM') lower the weight and hey, M'nome goes faster. The weight of the rig and forces on the rig reduce the roll period on a yacht tho.

It is quite well explained here:

The aim on the P98 was to raise the 'GM' and SilverDee for that matter.

http://en.wikipedia.org/wiki/Metacentric_height



So thanks for that, appreciated, but I'm still no expert.:ambivalence:

 

[jfm]

I think we're violently agreeing. The metronome is an upside down grandfather clock. When you raise the weight, you move it further from the roll axis, and that slows it down. Exactly same as lowering the weight in the g'father clock

That's the point. To increase roll period, it doesn't matter (for roll period purposes) which direction you move the weight in, so long as it is away from the roll axis. The best place to stow that princess 98 would be on the end of a very long fin keel, but that aint allowed so the guys on the ship have only two choices, which is to put yachts in the hold or on the deck. Aka close to the roll axis or away from it. They choose "away from it" of course with the p98 to slow the rolling, ie on deck

 

[RogerRat]

I think we're violently agreeing. The metronome is an upside down grandfather clock. When you raise the weight, you move it further from the roll axis, and that slows it down. Exactly same as lowering the weight in the g'father clock

:ambivalence: Hey, I've never had a violent agreement before, pistols at dawn, you bounder, let's miss in style!

Seriously, thanks for putting me straight.

Roger.

 

[westernman]

Can you tell us why you picked the John Deere 6068AFM? Why the AFM and not the TFM50?

 

[Bajansailor]

Can you tell us why you picked the John Deere 6068AFM? Why the AFM and not the TFM50?

I am also interested, hence bumping this thread back up to stop it 'dropping off' the bottom of the Forum.

Here is a link to the 6068AFM - http://www.deere.com/wps/dcom/en_US...ulsion_certified/6068_series/6068AFM75_A.page

And a link to the 6068TFM50 - http://www.deere.com/wps/dcom/en_US...on_non_certified/6068_series/6068TFM50_C.page

 

[westernman]

I am also interested, hence bumping this thread back up to stop it 'dropping off' the bottom of the Forum.

Here is a link to the 6068AFM - http://www.deere.com/wps/dcom/en_US...ulsion_certified/6068_series/6068AFM75_A.page

And a link to the 6068TFM50 - http://www.deere.com/wps/dcom/en_US...on_non_certified/6068_series/6068TFM50_C.page

Bump again.

 

[rbcoomer]

Just caught up with this one again, This has to be one of the most diverse threads outside of the lounge - drifted from boats to car designers and torsional stiffness, cargo and mast physics, metronomes, gold ingots and seawater flushing... With two-and-a-half months wait for engines, I wonder where we'll 'drift' next...

Impressive layout SD - amazing what's squeezed inside that hull! Even more so when you see the pics as it doesn't appear at all cramped either!

 

[MapisM]

LOL, give SD a bit of time, and at the very least we'll drift towards u/w lights and the ancam....
...not to mention a hi/low platform or, heaven forbid, an upgrade to STAR stabs!

On a more serious note, I couldn't agree more on your last statement.
That was exactly my thought, when I saw SD pics.
I wish I had 70% of what's inside SD on my boat, in spite of the fact that they are just about the same LOA.

 

[westernman]

I am also interested, hence bumping this thread back up to stop it 'dropping off' the bottom of the Forum.

Here is a link to the 6068AFM - http://www.deere.com/wps/dcom/en_US...ulsion_certified/6068_series/6068AFM75_A.page

And a link to the 6068TFM50 - http://www.deere.com/wps/dcom/en_US...on_non_certified/6068_series/6068TFM50_C.page

Bump again!
Please do tell us.

 

[jimmy_the_builder]

Bump again!
Please do tell us.

Give him a chance. Bumping the thread every day isn't going to help.