Swim platform issues

[pan]

PRINCESS have suggested putting 750KG of ballast in the Lazarette and they calculate this would bring the stern down by 43mm. They have also admitted that the boat rises by 86mm from full to empty. Considering my boat is not giving sufficient depth over the swim platform when 3/4 full of fuel I am at a loss to understand how they calculate 43mm extra depth from 750KG of ballast will offset 48mm further rise from reducing fuel from 75% to 20%. ANY IDEAS ANYBODY???

Utterly ridiculous…! Was this suggestion from Princess (manufacturer) or someone they authorised to look at the problem? If this was from the factory, my opinion of Princess has plummeted to zero and would never consider buying a boat from them. After all the sales talk to me at SIB about 'infusion' benefits of weight & fuel economy, to suggest this solution seems that it is more about cost cutting than anything else.

The real solution is to replace the hydraulic lift system with one that has a greater range! not chucking weight into the bilges…

I think you need to identify who is giving this opinion, before Princess's reputation is totally trashed.

Pan...

 

[PRINCESS 56 OWNER]

Herewith the actual latest words from Princess [The Factory PYI] about the problem and I quote;

"Further to our investigations on P56039, we can confirm the following:

We have performed some check measurements and can confirm that the boat is as designed in relation to the bathing platform mechanism. It is rotating correctly and has an “immersion” of 400mm below DWL. This is as per all other Princess 56.

According to our sea trial records, this particular slot is very light – it appears to be the lightest of the 36 slots for which we have data. Judging by the water mark on the antifoul, this would also indicate that the boat is lighter than average.

Attached is an annotated sketch of the range of flotation. Taking the water mark as a reference, we appear to have some 448mm of water above the platform top. We have assumed that the water mark is marking where the yacht is in her deepest draft (photos attached). As the fluid levels on board drop off, this does reduce the quantity of water above the platform, to an in extremis 362mm in the Minimum Operating Condition (as per the Stability Statement in the Owner’s Manual).

Our suggestion would be to add ballast to increase stern immersion. Adding 750kg to the aft lazarette would lower the transom by 43mm. This will have a very minimal effect on performance. We estimate this to be approximately half a knot and this will still ensure that the boat remains within the range advised in the brochure specification".

Per my previous comment even if they add approaching 0.82 of a Ton of Ballast in line with their suggestion this will still leave me worse off in terms of depth of water over the platform when at 20% fuel. Staggeringly they admit in their figures that there is only 362mm of water over the platform at the lowest level of fuel and surely they can't believe you can float a Williams 325 in a pond with that depth let alone in conditions where there is any movement out on the water.

 

[jimmy_the_builder]

Well, just in the interest of getting all the info on the thread, according to Williams the 325 draws between 0.21m and 0.3m.

Your quote above does raise another interesting question - if your P56 is light by 750kg against the design weight (which seems to be the implication of the statement you've quoted) - where/how has this lightness been achieved??

 

[PRINCESS 56 OWNER]

It would appear that they have saved nearly a Ton somewhere as this is what they are suggesting will bring it down to it's DWL.

 

[pan]

Herewith the actual latest words from Princess [The Factory PYI] about the problem and I quote;

"Further to our investigations on P56039, we can confirm the following:

We have performed some check measurements and can confirm that the boat is as designed in relation to the bathing platform mechanism. It is rotating correctly and has an “immersion” of 400mm below DWL. This is as per all other Princess 56.

According to our sea trial records, this particular slot is very light – it appears to be the lightest of the 36 slots for which we have data. Judging by the water mark on the antifoul, this would also indicate that the boat is lighter than average.

Attached is an annotated sketch of the range of flotation. Taking the water mark as a reference, we appear to have some 448mm of water above the platform top. We have assumed that the water mark is marking where the yacht is in her deepest draft (photos attached). As the fluid levels on board drop off, this does reduce the quantity of water above the platform, to an in extremis 362mm in the Minimum Operating Condition (as per the Stability Statement in the Owner’s Manual).

Our suggestion would be to add ballast to increase stern immersion. Adding 750kg to the aft lazarette would lower the transom by 43mm. This will have a very minimal effect on performance. We estimate this to be approximately half a knot and this will still ensure that the boat remains within the range advised in the brochure specification".

Per my previous comment even if they add approaching 0.82 of a Ton of Ballast in line with their suggestion this will still leave me worse off in terms of depth of water over the platform when at 20% fuel. Staggeringly they admit in their figures that there is only 362mm of water over the platform at the lowest level of fuel and surely they can't believe you can float a Williams 325 in a pond with that depth let alone in conditions where there is any movement out on the water.

So Princess PYI state that your 'slot' (oops boat sorry!) is lighter than average, but without any actual figures (so assume they have no idea, but could be a good excuse perhaps), estimate you will only lose 0.5kt, but presumably no guarantee? No figures for loss of fuel economy? The wording looks to me like the start of a defence strategy, rather than looking for a sensible solution, for a customer who has spent £1m on one of their 'slots' (sorry boats)

As you say 'staggered', but referring back to a previous thread about Princess warranty, I have serious doubts about how Princess look after their customers!

 

[petem]

Well, just in the interest of getting all the info on the thread, according to Williams the 325 draws between 0.21m and 0.3m.

Your quote above does raise another interesting question - if your P56 is light by 750kg against the design weight (which seems to be the implication of the statement you've quoted) - where/how has this lightness been achieved??

My thoughts exactly!

 

[Deleted User YDKXO]

Just an idea. If this does come down to the only solution being to add ballast maybe, instead of just lobbing some lead weights into the lazarette, Princess could offer to fit a 2nd generator or a watermaker or something as a gesture of goodwill so that at least you're carrying 750kg of something useful

 

[mil1194]

Just an idea. If this does come down to the only solution being to add ballast maybe, instead of just lobbing some lead weights into the lazarette, Princess could offer to fit a 2nd generator or a watermaker or something as a gesture of goodwill so that at least you're carrying 750kg of something useful

VERY good thinking......much cheaper than even thinking about a legal issue.

 

[jimmy_the_builder]

Just an idea. If this does come down to the only solution being to add ballast maybe, instead of just lobbing some lead weights into the lazarette, Princess could offer to fit a 2nd generator or a watermaker or something as a gesture of goodwill so that at least you're carrying 750kg of something useful

Great thinking Mike. You can see that this owner has a similar prob trying to get his bathing platform to stay underwater, and in line with your suggestion has rejected ballast in favour of 'something useful'...

(with apologies to the OP, it was just an excuse to post the picture, sorry... )

 

[pan]

VERY good thinking......much cheaper than even thinking about a legal issue.

Or perhaps fitting a system that actually works rather than something the owner did not specify (assuming his spec what was what he wanted) the cost difference would be negligible to Princess…. unless there is a problem with all the P56's ? Which may be a bigger problem for them!

Presumably all the op wants is a solution for his boat, not simply reject the whole boat, so why should this need to go down the legal route, unless Princess don't care about their customers and reputation?

 

[PRINCESS 56 OWNER]

At the Risk of being frivolous it might not solve the problem as their appears to be more "Floatation Devices" in evidence than what you might call "Ballast"!!!

 

[jimmy_the_builder]

At the Risk of being frivolous it might not solve the problem as their appears to be more "Floatation Devices" in evidence than what you might call "Ballast"!!!

Nothing wrong with a bit of frivolity to lighten the mood! (I could have found a, er, better picture, but this is family forum, after all.... ).

I'm quite interested in this point about your boat being light compared to the other 36 boats mentioned in your previous quote. Is it the case that your spec is especially light - eg have you got a spec comparison sheet between your boat and the other 36? Have they all got big gennie/aircon/gyro/hard top/passerelle or something, and you haven't? [I wonder if the factory make a design assumption about actual spec levels and attendant weight, vs the displacement of a theoretical minimum weight?]

 

[Nick_H]

If I read the Princess reply correctly, they are saying that the OP's boat has a minimum depth over the fully lowered platform of 362mm (ie. at low fuel levels). Jimmy informs us that the Williams has a draft of 300mm max. If both those are correct, then is it just the chocks that get in the way? If so, the easiest solution must be to design some very thin chocks?

It surely can't be this simple as lots of people have already looked at the problem, can it?

 

[jimmy_the_builder]

If I read the Princess reply correctly, they are saying that the OP's boat has a minimum depth over the fully lowered platform of 362mm (ie. at low fuel levels). Jimmy informs us that the Williams has a draft of 300mm max. If both those are correct, then is it just the chocks that get in the way? If so, the easiest solution must be to design some very thin chocks?

It surely can't be this simple as lots of people have already looked at the problem, can it?

Good point. Who supplied the chocks? Are they from the OP's prev P54?

 

[MapisM]

According to our sea trial records, this particular slot is very light – it appears to be the lightest of the 36 slots for which we have data. Judging by the water mark on the antifoul, this would also indicate that the boat is lighter than average.

Blimey, are these guys for real? And they even WROTE that, as I understand?!?

Let's see what we have got.
To start with, a boat weighing less than 25T dry, according to the builder specs.
And they are suggesting that a 750kg ballast astern would bring the stern draft of your specific boat "back to normal", so to speak.

Now, forget the effect on performance. The first thought is that there isn't much else other than the main GRP shells, where that weight might have been lost.
But it is difficult to know (I mean, without some inside knowledge - the builder must know exactly, of course), the weight of the bare hull and superstructure.
Anyhow, that's bound to be substantially less than 25T. I would think that if I guess 15T I'm probably over-, rather than underestimating.
Besides, it's pretty obvious that they can't have "lost" all the weight at the stern. More than likely, the saving is proportionally distributed along the whole hull.
In other words, if they think that 750kg placed astern would bring the STERN draft back to normal, it means that the whole boat must actually be MUCH lighter than that when compared to the standard specs, because she should have a lower draft along her whole w/l.
Which is reflected in the other number you quoted: 86mm from full to empty. Since the full to empty difference is about 3T, the 43mm they are aiming at with the stern ballast implies that the "weight lost" in the whole hull is actually half of those 3T, i.e. 1.5T.
Which incidentally is the double of the suggested stern ballast. Sanity check: does that makes sense? Imho, yes.

So, what they are saying is that a hull 10% lighter than normal is still within specs, and that doesn't affect its strength in any manner.
Sorry, but I for one don't buy that.
And even if that would be true, why aren't they aiming at that 1.5T weight (and costs) reduction on all hulls!?!

...but hang on, there's another sanity check that popped to my mind.
By coincidence, in my boat the full to empty draft difference is roughly the same, 8 cm or so.
But she's a bit smaller, and the weight difference is much higher: 5 vs. 3 tons, and that rang a bell.
So, I calculated what should be the w/l footprint corresponding to a draft increase of 83mm with 3T, and it's about 35 square meters, in sea water.
Now, I can't think of a more appropriate usage of the expression "doesn't hold water" than in the case of this number, which doesn't make any sense for a 56'.
In other words, the 83mm they gave you is plain wrong.
Which in turn means that if 43mm is what you need, you will NOT get it with 750kg.

And all that without even start considering the effects on performance.
Just as an example, for consistency with their theory, your boat should now be half a knot FASTER than normal - is she?
Regardless, there are other excellent reasons for not wanting a 750kg stern ballast to solve a problem like this.

In your boots, I'd scream at the builder, asking that they put on your case someone who can handle at least some basic math PDQ.
On the positive side, I'd rather have a problem like yours with Princess than with any other Brit builder.
They are surely able to find a proper solution, if they want to.

Best of luck.

 

[MapisM]

the design of the Princess 56 is top rate, imho. Then someone in Plymouth saves a few quid by fitting rubbish hardware to the boat, like this platform mechanism or incandescent lighting or whatever, and lets the whole side down.

ROTFL, I suppose that "whatever" includes a notorious curved equipment.
So, eventually we are understanding why it was chosen for the P56.
Nothing to see with vectorial analysis, 'twas all down to someone in Plymouth saving a few quids...!

Sorry jfm, but I REALLY couldn't resist this one.....

 

[petem]

Great thinking Mike. You can see that this owner has a similar prob trying to get his bathing platform to stay underwater, and in line with your suggestion has rejected ballast in favour of 'something useful'...

(with apologies to the OP, it was just an excuse to post the picture, sorry... )

750kg is more like 12 birds so a great idea.

 

[NGM]

If I read the Princess reply correctly, they are saying that the OP's boat has a minimum depth over the fully lowered platform of 362mm (ie. at low fuel levels). Jimmy informs us that the Williams has a draft of 300mm max. If both those are correct, then is it just the chocks that get in the way? If so, the easiest solution must be to design some very thin chocks?....QUOTE]

in order to follow the profile of the Williams I doubt the chocks could be much lower than 40mm, this would only allow 22mm of clearance, fine in dead calm conditions but with any kind of chop the same problem arises.

 

[henryf]

A lot of points raised here. On the face of it adding ballast does seem an odd way to go unless the boat in question is unusual in terms of spec, no generator, never carries fresh water on board, runs with low fuel and so on.

Certainly worth looking at the tender chocks being used.

So what would a typical bathing platform drop be? Actual measurements rather than guesses please. I've never owned a boat with a hydraulic platform, always some form of crane if anything and they are effective. You can work around a bit of swell which I imagine can cause difficulty on a hi-low bathing platform.

So what is a normal or recommended drop ?

More and more boats seem to be fitted with moving platforms or variations so I think it would be a useful thing to know.

I presume there is an added complication with movable platforms in that you don't want them too close to the water when up and closed otherwise the platform acts as part of the hull or a giant trim tab when underway, particularly when it is a nice deep platform. If in contact with the water a lot of stress will be placed on it as it supports the vessel.

Henry

 

[vas]

Following with interest, and as others posted I find Princess and their written reply rather poor!

I'd push Princess to act on one of the two following options:

A. replace the platform with a suitable one with decent travel (as per JFM's comments earlier in the thread)
B. demand a hydraulic passerelle that would first help you sort out the williams, and second make the boat suitable for Med mooring thus increasing the resale value

good luck

cheers

V.

PS. apologies if the boat is already fitted with a passerelle but I've not seen any such mention