Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: ruffair on September 18, 2007, 08:47:58 AM

Title: Slipway Sentinel...Stabilisers?
Post by: ruffair on September 18, 2007, 08:47:58 AM
Hi all

Can anyone tell me if it worthwhile building the Sentinel with active stabilisers?  Do they make a worthwhile contribution to the boats handling?

Thanks in advance

Ruff
Title: Re: Slipway Sentinel...Stabilisers?
Post by: dougal99 on September 18, 2007, 11:48:19 AM
I was advised to make mine active by two independant builders of the kit and have done so. Unfortunately, I have yet to finish the build, but getting there.

Doug
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Robert Davies on September 18, 2007, 01:04:09 PM
Do they make a worthwhile contribution to the boats handling?

In my experience having the fins fixed works very nicely. The moving fin setup recommended by ModelSlipway is not actually a stabiliser as such, as it is linked purely to the rudder actuation and not to the vessel's roll state as well. In a quiet moment I considered a sort of pendulum to control the stabilisers via the vessel's roll angle, but my head started to hurt when I began to see a need for the pendulum to be damped to prevent excessive fin movements.....

The other issue you need to be very careful of with the Sentinel = weight, they frequently need some jiggery pokery to bring them UP to the waterline. Indeed I was talking to the chap from Slipway (Lawrie?) and he indicated that the hull had an additional quarter inch added to it's depth to enable the model to stand any chance of meeting it's waterline. Love mine to bits btw, and have sailed it in VERY heavy seas - ie disappearing from view in the troughs between the waves - I just made sure the superstructure and hatch was firmly attached and no trouble was experienced at all :)

-Rob

-Rob
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Martin [Admin] on September 18, 2007, 01:15:14 PM
What about one of the micro gyros that are available for the small electric helicopters?
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Robert Davies on September 18, 2007, 01:40:16 PM

Hmm.... A microgyro....

Could well work.... My new 6EX 2.4ghz has a switch marked 'gyro'....

Weight is STILL the issue I'm afraid... Extra linkages, servos etc....

I WAS TALKING ABOUT THE BOAT!

;D

I'll have to have a word with my model heli flying associates.

-Rob
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Bluebird v2 on September 18, 2007, 03:30:22 PM
hi all

food for thought :

The set up I am about to try and explain is very much similar to the one I made and use in one of my models.  Its very simple to make; and only requires a minimum of a few inexpensive components.  It utilises an electronic servo tester (I wonder who on this Forum makes and sells them) two cogs, one large and one small, two old biro springs, some lead sheeting, a bit of brass rod and either plastic or brass plate to make a guide.

The most difficult part is calculating the two sizes of cog required; if we have a look at the drawing or scribble you can see:-

XX represents a modified servo tester;
A is the small cog which is connected straight to the variable resistor on the servo tester;
B is the larger/drive cog
C is the two dampening springs (made from old biro pen springs)
D is the lead weight which is a horse-shoe shape
E is the guide (this prevents the weight from trying to move ford and aft - when the boat is pitching)

What we must calculate is the maximum swing of weight D; from one side to the other.  This in turn moves cog B which in turn moves cog A; exactly half of the movement of the variable resistor in the servo tester.

In my model the output from the servo tester goes through a 'Y' lead to two independent servos which drive the stabilisers.   You could use one servo with linkage driving two stabilisers.   What we must remember is, if port stabiliser tilts upwards, the starboard tilts down, so, therefore if the boat rolls to port - port stabiliser tilts up and starboard tilts down - thus creating a screwing effect in the opposite direction to the roll of the boat.

Hope this is of some help and as I say, food for thought, well it does work (at least for me).

Aye
John E
Bluebird
Title: Re: Slipway Sentinel...Stabilisers?
Post by: DickyD on September 18, 2007, 03:40:41 PM
Brilliant!! O0
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Robert Davies on September 18, 2007, 04:51:10 PM

Excellent  John!

Springs for damping....

Step down gearing....

Hmmm....

:D

-Rob
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Martin [Admin] on September 18, 2007, 06:19:53 PM
Alternatively, if you have cash to burn, the submarine boys have "Auto levelers" that I imagine could be employed.
Title: Re: Slipway Sentinel...Stabilisers?
Post by: ruffair on September 28, 2007, 02:13:48 PM
Hmmmm....fifty/fifty then...!
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Bluebird v2 on September 28, 2007, 02:36:11 PM
Ruffair,  to be quite honest, I should not think having operating stabilisers on the model would make any 'noticeable' difference.   To be honest with you, its a bit of a gimmick - in my case I did it to see if it could be done (with the Leeds Castle).   Even when I switch the stabilisers off, you cannot see any difference.

Where I think it may make a difference, would be in the hull of a modern warship, where the hull is long and thin and prone to rolling.

aye
John e
Bluebird
Title: Re: Slipway Sentinel...Stabilisers?
Post by: ruffair on October 03, 2007, 07:59:59 AM
Thanks John.  That's made up my mind.  They are going to be fixed.  I just can't see the point of adding the extra complexity.

Cheers

Ron
Title: Re: Slipway Sentinel...Stabilisers?
Post by: FullLeatherJacket on October 03, 2007, 08:50:13 AM
Ron
My own plank-on-frame model of Nellie, which was the origin of the Slipway kit, is 6mm shallower in the draft than the kit version yet shows absolutely no signs of rolling. The stabilizers are resolutely epoxied in place!
FLJ
Title: Re: Slipway Sentinel...Stabilisers?
Post by: badbunny on October 04, 2007, 08:11:43 AM
RLJ, I'm confused, :-\  Is 'Nellie' a free scale version of an Island Class cutter, that Model Slipway based the Sentinel on, or did I lose the plot?
Pete.
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Bluebird v2 on October 04, 2007, 10:03:21 AM
hi there badbun

Basically, FLJ built the original kit that Model Slipway based theirs on.  All the good points and all the bad points on the Sentinel blame FLJ for  {-)  he also did all of the plans and instructions for Model Slipway's kit. Bit of a dark horse this FLJ isnt he  :D

aye
john e
bluebird

No bad points in the kit but, I just liked saying it  O0 {-) :angel: :P
Title: Re: Slipway Sentinel...Stabilisers?
Post by: badbunny on October 04, 2007, 12:05:07 PM
Hi, I was just confused about the name 'Nellie'. Is this an in-joke that I'm not getting?  ???

Pete.
Title: Re: Slipway Sentinel...Stabilisers?
Post by: FullLeatherJacket on October 04, 2007, 01:29:37 PM
Pete
"Nellie" is the name that Sentinel is known by to her crew, one of whom was the inspiration behind my model of her.
FLJ
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Martin [Admin] on October 15, 2007, 01:43:36 PM
I saw one of these in the water last week..... she rolled quite a bit.  :o
Can anything be done to minimise that? .....yes I do have the kit to build.
Title: Re: Slipway Sentinel...Stabilisers?
Post by: HS93 (RIP) on October 15, 2007, 01:56:07 PM
Get a keel of a yachts .

Peter
Title: Re: Slipway Sentinel...Stabilisers?
Post by: Martin [Admin] on October 15, 2007, 02:55:29 PM
Do you know Peter... I WAS actually thinking of doing that!  :D
A sort of clip on running keel like some model Thames barges do.
Title: Re: Slipway Sentinel...Stabilisers?
Post by: HS93 (RIP) on October 15, 2007, 03:00:38 PM
I have seen it on some small ww1 type naval boats 4 stack jobs that are very narrow , it does make a difference how they sail ,