Getting your Cat off the dock

[mark_morwood]

Originally Posted by admiralslater

This is my solution, I will put in one note first. After experimenting with the engines I now use both as one, I found that the boat rotates better this way. BTW its cats that I own.

Back to the question at hand. Since you wanted to go out bow first I would
1 place a large fender as far aft as possible.
2 attach a spring from the stern as far up the dock towards the bow as possible.
3 put both engines in reverse enough to hold the boat but not more.
4 release all lines except the spring.
5 increase throttle until boat rotates out far enough to allow you to clear what you need to clear.
6 put engines in forward and then release spring not the other way around. Use enough power to get steerage.
As for the sharp corner that is where twin screws pay just don't stop the boat from moving forward or the wind will catch you.
That's what I would do. Any other takes on this

That sounds like a good suggestion to use the engines together with a spring line if you are trying to rotate the boat off the dock against a strong wind. I can see how it would give you more turning moment than the "normal" split engines. It was not something I had thought of so now i have another tool in the tool bag to try sometime - thanks.

So far, I've only had to rotate off against 15 knot cross-winds and the split engine approach worked fine. I've found a real advantage of splitting the engines is that if you are careful to play them so you don't roll the fender forward or aft along the dock, you don't need any dock lines, so there is one less thing to take care of when you have rotated out and are committing to leaving. The last thing you want is that spring line to not come clear as you leave - as pulling away requires commitment to ensure you don't blow back on.

To the original question, I would have had trouble as he was trying to leave bow first. I can't rotate as well off a fender at our stern as the shape of the sterns makes it hard to keep a fender right aft to avoid the stern hitting the dock. It limits how far I can rotate the bows off the dock. It is much easier on our boat to put a big fender right at the bow and rotate the stern out. This does have the disadvantage that I am maneuvering out in reverse which gives me fewer steering options than going forward. However rotating off the bow lets me use prop wash on the outboard rudder to help with the rotation, whereas rotating off the stern (in reverse) the prop wash doesn't assist.

The other advantage for me of rotating against the bow, is it is the same setup we use when coming onto a dock against the wind - a big fender on the bow - approach at a relatively steep angle - drop a short bow line over a cleat on the dock - then split the engines and rotate the stern in - drop on the stern line - finally rotate the other way against the stern line to bring the bow in and adjust the bow line.

Now if I could just work out a way to reliably communicate to "helpers" on the dock to just let/help my crew drop/throw the bow line doubled over the cleat so we can control it, rather than the dock helper grabbing it and locking it off, or worse trying to pull it in as I try to rotate the stern in against it!

Mark

[admiralslater]

Mark, I understand about having a curvy stern (insert joke) .my 36 is relatively flat whereas the Outremer 45 is rounded which is a little more difficult.
I must say that for me using the engine as a spring (if I understand correctly) makes me nervous because even though the boat is technically not moving,when you start to play the engines you might start to be pushed to the Lee.
If you use a spring line and issues arise the wind will just take you neatly back against the dock.
Shore side help. They mean well.
If you have a long line and it can be lighter than your regular line ie old halyard try this. Fix one end to the appropriate cleat on the boat, loop around the dock cleat and come back to the cleat on the boat. This takes away any extra rope that someone might want make fast and is also obvious when it is time to cast off.
It is possible to lay the line around the dock cleat in such a way as to allow the line to slip off the cleat as you motor out. I have done this in a strong wind with boats in front and rear of me single handed
David

[mark_morwood]

Yep - the other engine acts as the spring line. I initially learnt this splitting the engines from a twin engine power boat captain during Yachtmaster training, but it is widely used on sail catamarans and from what I've observed most of the big twin engined ferries etc. A bunch of the other catamaran cruisers on here have described the same method. I'm not sure I understand your concern about being pushed to the Lee? It's pretty straight forward to control the position of the boat along the dock either by decreasing or increasing the power on the engines. And if you decide you can't get enough angle off to leave the dock, you can just let the wind push the boat back on to the dock as you ease up on the engines.

Mark.

[thinwater]

Originally Posted by mark_morwood

... So far, I've only had to rotate off against 15 knot cross-winds and the split engine approach worked fine. I've found a real advantage of splitting the engines is that if you are careful to play them so you don't roll the fender forward or aft along the dock, you don't need any dock lines, so there is one less thing to take care of when you have rotated out and are committing to leaving....

Exactly my experience. I have used this method when my boat has been parked in with front and rear spacing down to within 2-3 feet of the theoretical minimum (boat measured on the diagonal). The reality is that the dock-side engine is 4-6 times closer to the dock and thus provides 4-6 times less less turning torque around the line. It can provide only very limited turning moment because it has little leverage.

And the point about "helpers" is dead on.

[Ulstue]

Once again the two engines offer a different maneuver to monohull.

If I can't dock off without a line, I don't use a spring. Use the line on the bow and put the dockside engin in revers and stern rotates out then without contact of the bow or the fenders to the dock.

[2hullvenus]

I do it like a monohull.

Loosen bow line, forget the spring line, tighten way up on stern line.

Due to the natural curvature of the boat's side, this points the bows sufficiently away from the dock to then:

1) untie bow line and give a final nudge to the bow, pushing it out farther
2) Run to the stern, grab the stern line
3) Jump onboard with the stern line
4) Secure stern line so it doesn't foul props
5) Run to helm and full throttle both engines straight ahead (which is away from the dock when bows are pointed out)
6) Use rudders as desired while getting steerage as she accelerats away from the dock.

Been doing this single handed method all my life. Has never failed me in any wind/current condition.

[admiralslater]

Originally Posted by mark_morwood

Yep - the other engine acts as the spring line. I initially learnt this splitting the engines from a twin engine power boat captain during Yachtmaster training, but it is widely used on sail catamarans and from what I've observed most of the big twin engined ferries etc. A bunch of the other catamaran cruisers on here have described the same method. I'm not sure I understand your concern about being pushed to the Lee? It's pretty straight forward to control the position of the boat along the dock either by decreasing or increasing the power on the engines. And if you decide you can't get enough angle off to leave the dock, you can just let the wind push the boat back on to the dock as you ease up on the engines.

Mark.

As for the blowing to Lee thing, I understand that the twin engine spring will work. I just like having the knowledge that if something happens in tight quarters that the boat ends up back at zero. Small point really.
What cat do you have and what HP.
David

[mark_morwood]

Originally Posted by admiralslater

As for the blowing to Lee thing, I understand that the twin engine spring will work. I just like having the knowledge that if something happens in tight quarters that the boat ends up back at zero. Small point really.
What cat do you have and what HP.
David

I agree about thinking about the possible failures. I have the opposite concern to yours - with both engines in forward or reverse against a spring line any failure of the spring line puts the boat into the boat ahead of you or the boat behind you - not that this sort of failure is likely on most docks.

Give the split engine approach a try and I think you'll find that it gives you more control and you don't have a highly loaded deck cleat, dock line, and dock cleat to worry about (particularly the risk of it failing to release cleanly).

I'm not against loading dock lines, we use a short bow-line, under considerable lateral load to swing the boat onto the dock against a wind. However the line is loaded at right angles to the dock so if something goes wrong with the line, we do not end up jumping forwards or backwards into the boats that are inevitably closer than you would like.

We have a Catana 48 with 2 x 35hp diesels.

Mark.

[mark_morwood]

Originally Posted by 2hullvenus

I do it like a monohull.

Loosen bow line, forget the spring line, tighten way up on stern line.

Due to the natural curvature of the boat's side, this points the bows sufficiently away from the dock to then:

1) untie bow line and give a final nudge to the bow, pushing it out farther
2) Run to the stern, grab the stern line
3) Jump onboard with the stern line
4) Secure stern line so it doesn't foul props
5) Run to helm and full throttle both engines straight ahead (which is away from the dock when bows are pointed out)
6) Use rudders as desired while getting steerage as she accelerats away from the dock.

Been doing this single handed method all my life. Has never failed me in any wind/current condition.

I did it like this or variants of this when I first got a cat, but learnt there are easier options. It's worth at least giving them a go. And to be accurate, this is in fact not the mono-hull way, it is the single engine way. Twin engine mono-hulls use split engines all the time.

Compare your above approach (which I do not think will always work in the situation some of us have been discussing - strong breeze directly on to the dock with obstructions fore and aft) to the split engine approach:

- Put a big fender at the very bow or stern, make sure all lines are doubled back to the boat
- Drop all the lines (the wind will hold the boat on to the dock - if necessary use slight fwd or reverse as you drop the last line to hold the boat still if the wind is partially along the dock)
- Split the engines and rotate either the bow or the stern to about 30 degrees off the dock
- Drive away in forward or reverse, depending on whether you rotated the stern or bow off the dock

Of course there are many different approaches that can be made to work. I think it's worth trying them all to see what works for you. You may be surprised to find out how many more options you have if you work your twin engines independently than if you treat them as a single unit.

Mark.

[FamilyVan]

^^^ there are circumstances where putting both engines in forward is more effective than a split. Using a bow spring to spring off a dock onto an onshore wind could be one of those circumstances.

You're able to generate more lateral thrust with this method because the thrust is vectoring off two rudders rather than one. A good strategy for this could be to clutch the inboard engine and feather the throttle on the outboard engine to control the rate of turn.

A split will of course provide greater rotation in place, but if its lateral thrust you seek, both engines ahead, both rudders hard over working against a spring line might be your best bet.

Sent from my XP7700 using Cruisers Sailing Forum mobile app

[mark_morwood]

Originally Posted by FamilyVan

^^^ there are circumstances where putting both engines in forward is more effective than a split. Using a bow spring to spring off a dock onto an onshore wind could be one of those circumstances.

You're able to generate more lateral thrust with this method because the thrust is vectoring off two rudders rather than one. A good strategy for this could be to clutch the inboard engine and feather the throttle on the outboard engine to control the rate of turn.

...

Definitely. Forward against a spring using prop wash from both engines over the rudders with the helm over would be hard to beat in terms of getting the stern upwind off the dock. I haven't had a case where split engines wasn't enough, but this approach is definitely one I would try if I needed.

Interestingly the seemingly mirror manuever using a stern spring and swinging the bows off using both engines in reverse would not get the same advantage because of the proximity of one engine to the rotation point and the lack of prop wash over the rudders.

[thinwater]

Originally Posted by 2hullvenus

I do it like a monohull.

Loosen bow line, forget the spring line, tighten way up on stern line.

Due to the natural curvature of the boat's side, this points the bows sufficiently away from the dock to then....

Monohulls have curvature, cats, not nearly so much.

cats have to get the bow MUCH further out, specifically because we are often parked between cats.

This will not work with a cat in strong conditions with tight company. Nope. In light conditions, yup, do that all the time.

[admiralslater]

Originally Posted by mark_morwood

I agree about thinking about the possible failures. I have the opposite concern to yours - with both engines in forward or reverse against a spring line any failure of the spring line puts the boat into the boat ahead of you or the boat behind you - not that this sort of failure is likely on most docks.

Give the split engine approach a try and I think you'll find that it gives you more control and you don't have a highly loaded deck cleat, dock line, and dock cleat to worry about (particularly the risk of it failing to release cleanly).

I'm not against loading dock lines, we use a short bow-line, under considerable lateral load to swing the boat onto the dock against a wind. However the line is loaded at right angles to the dock so if something goes wrong with the line, we do not end up jumping forwards or backwards into the boats that are inevitably closer than you would like.

We have a Catana 48 with 2 x 35hp diesels.

Mark.

I will give it a try when I get back to Grenada in January. Semantics really we both have different things that we mistrust .likelihood of either failure is low.
We looked at a 431 before finding the Outremer 45. Both in grenada
David

[valhalla360]

Originally Posted by FamilyVan

^^^ there are circumstances where putting both engines in forward is more effective than a split. Using a bow spring to spring off a dock onto an onshore wind could be one of those circumstances.

You're able to generate more lateral thrust with this method because the thrust is vectoring off two rudders rather than one. A good strategy for this could be to clutch the inboard engine and feather the throttle on the outboard engine to control the rate of turn.

A split will of course provide greater rotation in place, but if its lateral thrust you seek, both engines ahead, both rudders hard over working against a spring line might be your best bet.

Sent from my XP7700 using Cruisers Sailing Forum mobile app

While technically true...

If you are running flat out on the up wind engine and she isn't pulling the stern around, I'm probably going to settle back down on the dock and wait for the wind to die off.

[2hullvenus]

**Note: I don't put my cats on docks that resemble parallel parking spots with obstructions fore and aft.

Don't care to play around with those situations sans bow thruster.

So, I purposefully dock where my simple, mono style, single engine techniques work.

I am anchored out typically, only touching docks for fuel/water... much easier than parallel parking.

So... the technique I mentioned certainly could get difficult with obstructions forward of the boat. Aft would be irrelevant. I concede this.