Lifting centreboard, opinions please

[WhiteHill]

Consider a 13 m monohull which has a lifting centreboard (centerboard) and twin rudders, which is manoeuvering/parking in a marina with plenty of depth. There is no current, no wind and its sails are down. Is she easier to manoeuvre/park (a) with the centreboard completely lifted; (b) with the centreboard down; (c) the centreboard position makes no difference? Thanks in advance.

[valhalla360]

We had a small cat with centerboards. Fairly similar in that it had 2 rudders and a central prop. Only difference is the prop was steerable, which introduced a slightly different operation.

Absolute pig with the boards up as there was nothing to stop her from sliding sideways. Put one of the boards down a foot and maneuvered great. It acted as a pivot point.

[TrentePieds]

You tell us :-)!

I don't think there are many other members with an Allures 44, so you are not likely to get an answer based on actual experience.

One is prompted to wonder why you would ask, although upon consideration of the design characteristics of the boat as shown in SailboatData and of several photos of the type on the hard, this particular sailor would think that the type is seriously handicapped as far as maneuverability at low speed and under power is concerned.

You asked, so forgive me if the following sounds harsh :-):

1) The boat's canoe-body is shaped, essentially, as that of a racing dinghy of 1/3 of her length, but, unfortunately, with a beam/LWL ratio rather greater than one would consider appropriate for such a dinghy, and with the maximum beam occurring a good deal further aft than is desirable.

2) The boat has twin rudders set so far outboard (necessitated by the characteristics noted in 1) above) that the prop wash from the saildrive cannot impact them.

3) The saildrive is set so far forward in the hull that "prop walk" will have a far lesser effect than is the case with a more conventional prop positioning.

4) The general underwater configuration of the boat appears to me to be such that the boat's natural "pivot axis", if the board is up, will be about halfway along your cabin window if you draw it onto the outboard profile given in SailboatData. If the board is down, then perhaps the axis would be two feet or so (60 cm or so) forward of that.

The conclusion must be that whether the board is up or down, the boat will be basically unsteerable at docking speeds when going astern, and only manageable with great difficulty when going ahead. With any current or wind present, these traits will IMO be seriously aggravated.

The normal, time-honoured and effective routines employed at low speed in single engine boats with conventional prop and rudder positioning by experienced boat-handlers simply cannot be brought into play in this boat given its configuration.

So returning to you specific questions, IMO there would be a slight, perhaps so slight as to be imperceptible, advantage in having the board down.

Here is hoping you get the hang of it. No doubt the boat is an "interesting" sailer :-)

All the best

TrentePieds

[Orion Jim]

Centerboards are designed to aid sailing performance, not maneuverability under power.

[Fore and Aft]

OJ you still need something to pivot on and help with lateral resistance when under motor.
We have backed out of our berth with the keel up and it felt like we were driving on ice. Pretty funny the first time it happened.
We had twin rudders as well but converted to a single rudder and our docking improved a 100%.
Cheers

[valhalla360]

Originally Posted by Orion Jim

Centerboards are designed to aid sailing performance, not maneuverability under power.

Try running thru an icy parking lot and then doing a sharp 90deg turn and see what happens. Then put some steel track spikes on the shoes and it works a lot better.

This is essentially what putting a board down does (not that you should be docking at full power). Without the board down, there is nothing dig in and change the direction. You just keep on going in the same direction but you do it sideways. If the wind kicks up, it will blow you around easily.

A bit of board down the boat no longer wants to slide sideways.

[WhiteHill]

Originally Posted by TrentePieds

You tell us :-)!

I don't think there are many other members with an Allures 44, so you are not likely to get an answer based on actual experience.

One is prompted to wonder why you would ask, although upon consideration of the design characteristics of the boat as shown in SailboatData and of several photos of the type on the hard, this particular sailor would think that the type is seriously handicapped as far as maneuverability at low speed and under power is concerned.

You asked, so forgive me if the following sounds harsh :-):

1) The boat's canoe-body is shaped, essentially, as that of a racing dinghy of 1/3 of her length, but, unfortunately, with a beam/LWL ratio rather greater than one would consider appropriate for such a dinghy, and with the maximum beam occurring a good deal further aft than is desirable.

2) The boat has twin rudders set so far outboard (necessitated by the characteristics noted in 1) above) that the prop wash from the saildrive cannot impact them.

3) The saildrive is set so far forward in the hull that "prop walk" will have a far lesser effect than is the case with a more conventional prop positioning.

4) The general underwater configuration of the boat appears to me to be such that the boat's natural "pivot axis", if the board is up, will be about halfway along your cabin window if you draw it onto the outboard profile given in SailboatData. If the board is down, then perhaps the axis would be two feet or so (60 cm or so) forward of that.

The conclusion must be that whether the board is up or down, the boat will be basically unsteerable at docking speeds when going astern, and only manageable with great difficulty when going ahead. With any current or wind present, these traits will IMO be seriously aggravated.

The normal, time-honoured and effective routines employed at low speed in single engine boats with conventional prop and rudder positioning by experienced boat-handlers simply cannot be brought into play in this boat given its configuration.

So returning to you specific questions, IMO there would be a slight, perhaps so slight as to be imperceptible, advantage in having the board down.

Here is hoping you get the hang of it. No doubt the boat is an "interesting" sailer :-)

All the best

TrentePieds

Many thanks, TP, your theoretical analysis is impressively spot-on to that which I've found in practice! Docking this boat with wind continues to be part of a steep and somewhat miserable learning curve. I'll leave the board down, the default position, and aim for 'practice makes perfect'.

[tweitz]

My Beneteau 323 has a lifting keel, twin rudders, and a conventional engine (not a saildrive). I never have the board down while docking because we do not have the depth at our dock. I find that the boat is easily maneuverable. Obviously the configuration of the hull makes a big difference, and there is a keel stub that would provide a lateral turning point, though not as much as with the board down. Although many people claim that the absence of prop wash across the rudders means there is no prop walk, I find that not to be true. When I reverse at very low speed, the stern moves to port in a perfectly controlled manner. I dock alongside, and my routine (with board up) is to aim at the bulkhead at a fairly sharp angle at slow speed. When the bow is close to the bulkhead I apply reverse and the boat turns to starboard, turning around the middle of the boat, not the stern, thus swinging the bow away from the dock. The reverse stops the forward motion and starts the boat's rotation, and the stern snugs into the dock.

[roverhi]

Have crewed on a 31' trimaran that has to have the board down to make the 90 degree turn into the slip without drama. With board up boat skids and makes too wide a turn to get in the slip with space available.

[Cadence]

Leave the board down a fraction to replicate the keel on a power boat.

[PineyWoodsPete]

Originally Posted by Cadence

Leave the board down a fraction to replicate the keel on a power boat.

...and you'll need a bow-thruster! Or someone on the bow with a 12' pole. Leave the board down as far down as possible for a pivot-point. With all the aft rudder area totally unbalanced, the bow will blow off in a heartbeat. Been there, done that...

[greensail]

I have a southerly 145 with a lifting keel. I always put it down when manoeuvring in a marina, to act as the pivot point. Without it, it slips sideways and is a real pig.

Bob

[Inanna]

I had 45' sailboat single rudder shaft, keel down 2.2m draft, keel up .65m, tight docking, impossible with keel up, a bit easier with keel half down. I guess with twin rudders it could be different. For me, definitely, at least half keel down.

[Leee]

Re centreboard:


Practice makes perfect. I have sailed a 15m aluminum twin rudder centreboard since 2010. I found it quite difficult to maneuver at first but eventually figured out what works. The following is about reversing into a slot: Keeping the centreboard at least partly down helps immensely as one person already mentioned. For instance, for Med mooring in a crosswind, one must keep up a reasonable turn of speed in reverse and utilize the bow thruster to compensate for the skating effect (which can be used to advantage). The nearest analogy I can think of is landing a plane in a strong crosswind where straightening out at the last moment is the safest way. Quite different than the fin keels I used to sail which were rear wheel drive sports cars by comparison and easy to back into a slot in any wind/current condition. You will get the hang of it. Use a little more speed than you would with a fin keel.

[Cadence]

All of this is supposition. What model boat, water depth in the marina, wind speed and direction, and current. One answer doesn't fit all situations. ( forgot the adage)