Shifting Batteries

Ian M · 01 June 2011, 21:55

Since putting my Osprey on the water I have been less than happy with the handling. It is difficult to put into words, but the clean, straight running of other Ospreys was simply missing. The obvious factor was that the boat listed to port when up and running, but the subjective impressions went further than that, it felt dull, wrong, and to be frank I have got to the stage where I just cannot put up with it any longer.
So, what to do about it

Sell the boat? No, there must be a reason for it.
If you are in the boat building line please look away now

I know that when building the boat I had put the batteries in the wrong place

My thinking was that I would often be running one up and so to trim the boat I'll put the batteries on the other side thinks I. Wrong

Everyone puts the batteries on the starboard side to counter prop torque. But many that I spoke to said that they could not see this being the whole issue, even a heavy house battery weighs a lot less than one passenger. But I have got to do something, so I'll start by putting the batteries in the right place

When I first built the boat I constructed a massively over engineered 'monster' to mount both the starter and house batteries and oil tank in the bottom of the console. This is in picture 1. So as you can see in picture 2, taken looking back from the bow, the console was quite full, but crucially, the weight of the batteries is over the port side. When I fitted the monster I screwed and Sikaflexed it into place - mistake number 2

If you look closely in picture 3 you can see what I thought would allow me to get the monster out if I ever needed to - cheesewires, as recommended on this very forum. These are OK if you can get a straight pull, but...............I think a suitable moral is if you fit something that you think will need to come out at any time DO NOT use Sikaflex

Pictures 4 and 5 show verious stages of removal of the monster, taking three days in all using a combination of Fein Multimaster (brilliant), and hammer and chisel. What a job

The lump hammer that you can see was not used, but I was re-assured to have it to hand

Ian M · 01 June 2011, 22:09

So now I have finally cleared the bottom of the console, but as you can see in pic 1 it was not without a little cosmetic damage. So repairs and a lovely new topcoat, pic 2, and I am back to where I was 3 or 4 years ago.

I have decided to build some Gucci new battery trays, which will have a nice foam lining to give my darling battteries the comfort they so richly deserve

You can see these liners in pic 3. 4 shows stages in the construction of the trays, around the foam liners, and 5 a completed tray - not perfect, but heck it's a battery tray, destined to live in the bottom of my console

Ian M · 01 June 2011, 22:18

Picture 1 - the heaviest (house) battery tray is mounted over the top over the under-deck trunking outlet.
Picture 2 - the house battery just fits.
Picture 3 - the second (starter) battery tray goes in
Picture 4 - and the starter battery goes in.
The oil tank is now mounted just to port of the starter battery. So I have kept the weight to the starboard side of the boat as much as possible.
Now I just need to add some water................

Chris · 01 June 2011, 22:52

What Offset did you give the engine and from the rear is the offset to port or starboard?

Ian M · 01 June 2011, 23:01

Chris, my transom has sometimes resembled graph paper with all the lines pencilled on it at various times checking and re-checking the offset. The upshot is that it is an inch and a half offset from the centre line to starboard. I have even checked that the engine is perfectly vertical - it is

Chris · 01 June 2011, 23:09

Quote:

Originally Posted by Ian M

Chris, my transom has sometimes resembled graph paper with all the lines pencilled on it at various times checking and re-checking the offset. The upshot is that it is an inch and a half offset from the centre line to starboard. I have even checked that the engine is perfectly vertical - it is

Thats fine then.

I think you are on the right track with the batteries. Just keep in mind that adding weight regardless of which side is not going to improve handling so anything you can do to lighten the load and regain the balance is going to make a difference.

I only had one battery in TB and although I agree having 2 is a nice to have I decided that one battery and a starting pack for emergencies kept it simple and light weight and in nearly three years I never had battery issues.

Looking at your construction methods and knowing that you spent a lot of time attending to the fit out is there a chance you have added lots of weight in other areas as well?

bedajim · 02 June 2011, 06:12

Quote:

Originally Posted by Chris

What Offset did you give the engine and from the rear is the offset to port or starboard?

Does port or starboard change then? if looking from the bow or stern ?

Jim

Ian M · 02 June 2011, 07:20

Quote:

Originally Posted by Chris

Looking at your construction methods and knowing that you spent a lot of time attending to the fit out is there a chance you have added lots of weight in other areas as well?

My construction methods

I don't know what you mean

There is probably a little more weight in the console structure than other similar units, but not massively so.
I have taken a reasonable amount of weight out by removal of the monster battery holder, and replaced it by relatively low weight items.
The only other structure of note is a substantial 2" A frame mounted well to the stern, the sternmost tubes fitting to the outside of the transom, but I think that this is offset by a relatively low weight engine.

Erin · 02 June 2011, 08:29

I think you need a heavier engine (Cue Gotchiguy

)

Incidentally, my Osprey also runs with a slight but noticeable list to port, and when it dries out it always falls to port even though the engine is offset to starboard. My battery is mounted on the port side, but I really can't see 20kg or so making that much difference. It's the same when using singlehanded and I'm pretty sure I'd be counterbalancing the weight of the battery 3 or 4 times over.

I wonder if Mike lays up the port side slightly thicker or his template for the fuel tank mounting position is slightly worn?

gotchiguy · 02 June 2011, 09:19

Quote:

Originally Posted by Erin

I think you need a heavier engine (Cue Gotchiguy

)

Hello!

Quote:

Originally Posted by Erin

Incidentally, my Osprey also runs with a slight but noticeable list to port, and when it dries out it always falls to port even though the engine is offset to starboard. My battery is mounted on the port side, but I really can't see 20kg or so making that much difference. It's the same when using singlehanded and I'm pretty sure I'd be counterbalancing the weight of the battery 3 or 4 times over.

It depends on the weather. In some seas, it is going to be the prop of the prop which will send you to starboard. At other times, the boat does seem to have a bit of a tendency to fall a bit to port underway. This is especially noticeable when I drive with GD next to me, the best way to conteract it is to have one stage of tab more on the port side, thereby lifting the stern and levelling it out. It is surprisingly effective. Our engine is offset 1.5inch to STBD and the battery is on the STBD side. When GD helms it is far less noticeable.

Hightower · 02 June 2011, 17:42

Do you remember last year when I took the helm of Jianna and threw her around a bit?

I didn't notice any noticable lean to port or instablility issues untill we were at 45 degrees in a tight turn to port when the back end let go a little.

Obviously it wouldn't have behaved the same as having one on board, but I thought all seemed fine?

Ian M · 02 June 2011, 17:44

So, the time arrived to try out Jianna on the water. Going down the Lymington river I realised that I had done something as she listed to starboard, not much, and entirely appropriate to just me sitting to starboard. but I had not had that before!
I got out to the Solent and gave her the beans. There are many words that I could use but fantastic will do! Not a hint of a list, and she has that precision and surefootedness that was missing before - just brilliant. So, a completely successful result. A couple of weeks graft and worth every minute. I would not believe that Mr Newton could have such an effect on a dynamic system.
Personally, I doubted that this fix would be the answer.
I have been thinking about this, and moving 45Kg of batteries should not have changed the turning moment sufficiently to have such a dramatic effect, but I think the effect is actually 90Kg, as not only have I added 45Kg to starboard, but I have removed 45Kg from the port side. Yes I know I am being simplistic, as turning moment is force x distance, but the proof of the pudding .....
Fantastic

I think that bottle of Highland Park is in for it

Ian M · 02 June 2011, 17:49

Quote:

Originally Posted by Hightower

Do you remember last year when I took the helm of Jianna and threw her around a bit?

I didn't notice any noticable lean to port or instablility issues untill we were at 45 degrees in a tight turn to port when the back end let go a little.

Obviously it wouldn't have behaved the same as having one on board, but I thought all seemed fine?

It's no wonder you didn't notice anything, you spent most of the time with the deck at 45 degrees

Seriously, come out for a spin sometime, and try the new improved Jianna..........

Hightower · 02 June 2011, 19:18

Quote:

Originally Posted by Ian M

It's no wonder you didn't notice anything, you spent most of the time with the deck at 45 degrees

Seriously, come out for a spin sometime, and try the new improved Jianna..........

You're on

And congrats on getting the result you wanted.

Hugh Jardon · 02 June 2011, 22:50

I am surprised that moving the batteries a bit would have such an effect, does that mean it will be unsatisfactory again if you take a passenger?

Ian M · 03 June 2011, 07:43

Quote:

Originally Posted by Hugh Jardon

I am surprised that moving the batteries a bit would have such an effect, does that mean it will be unsatisfactory again if you take a passenger?

As the boat gets loaded I am sure that the effects will be masked, but I suspect that I will still see an improvement in the 'feel'. Certainly the reverse was true - my eldest son, weighing in at something over 12 stone commented on the 'tilt' (to port) as he put it, and with him on board the boat still felt less surefooted than I would have expected.
Unfortunately I am going to have to wait for a little while before I can put this question to a practical test.