My Prestige 560 is sinking (well not quite yet)

[danvan]

Hi everyone,

I have a Prestige 560 moored in Port Vauban in Antibes which I purchased new from Ancasta in 2017, which has Cummins zeus pods.

Whilst the boat literature suggests a top speed in excess of 30kn is achievable, in real life over the past 2 years I've basically achieved 28kn day in and day out. However so far this year I'm only getting to 23kn, and the max revs has fallen from 3030rmp to 2800rpm.

The Cummins engineers have checked the engine and reported it is in fine condition though when they did the service, they actually replaced one of the pods (under warranty). The only thing they can think about is that the boat is sitting heavy in the water - the photo below shows my exhaust half under water (the other photos is of another 560 with the exhaust in the right location).

However no-one can work out why the boat is lower in the water this year to last. FYI when this photo was taken (on Monday) the water tanks were completely empty and fuel at 60% - even when the water tanks were full last year the exhaust was always way above the water. There is also no water in the bilges. The boat doesn't have any new toys added this year, in fact we removed the 280kg tender when we took the photo.

I'd be really grateful if anyone has any ideas on what could be making the boat sink - Ancasta in the UK are being really helpful - but Prestige are not........(their only idea so far is to change the propellors at a cost of >10,000!)

Thanks very much in advance.

 

[Mr Googler]

Water inside the submersible bathing platform? Is it solid or cored or hollow?

Wouldn’t take huge amounts I imagine as it hangs out the back so lever forces etc...

 

[jrudge]

If it was defiantly higher last year then it can only be down to one thing - weight.

I appreciate you have looked as fuel, water etc but other than a change in water salinity nothing else is going to change the water line.

This would seem also to be validated by the slower speed etc. I beleive that some ( all?) lifts can measure the weight they are lifting and I wonder if you start with a lift and replace to water to get a weight?

I assume that the £10k bill was proposed to be met by you? Pod replacement seems expensive for someone.

I suspect jfm is you man for dealing with the manufacture. I suspect your case or otherwise will depend on when the performance issue( 28kts) was first raised with them.

 

[Divemaster1]

The exhaust outlet on the other 560 (although from Stb side) appears to be higher up on the hull and the anti foul and copper stripe also seems to be higher up against the swim platform/aluminium strip... also, your overhang (where hull/swim platform splits) appear longer than the other boat ... Could just be picture angle though ....

 

[luptonj]

Have a look at the bow and see if you can tell whether it's sitting lower or higher than before?
Is the boat sitting level or down on port or starboard?
Will give some indication where the extra weight has been added.

Then start looking for dead space that could be holding a substantial amount of water. In general anything flat or square will have some dead space behind or below it.

If there's nothing obvious, then I'd say take the boat out of the water for 2 weeks and ask a surveyor to check the moisture levels along the hull, if there is an amount of water somewhere it should show up.

 

[kashurst]

A 560 is a big boat so the usual dinghies/ribs/junk etc shouldn't bother it. Only ever getting 28Knots from new is OK but if everything else is the same and the props and hull are clean and you can only get to 23 knots something is wrong.
I would book a lift and a very good surveyor. Boats don't get that much heavier without good reason.

 

[CLB]

Your waterline looks pretty grubby, what’s the rest of the hull like? Fouling, and not much of it either, will slow the boat considerably.

 

[julians]

+1 for fouling. When was the Hull last cleaned?

 

[hullabaloo]

does the 560 have a balsa wood core hull?

 

[stelican]

We had a Fairline Squadron 50 on which the hollow bathing platform filled up with water and this sat stern down bow up considerably.

 

[Portofino]

Cored hull below the waterline has breached and soaked up literally tons of water.
Some water may have sodden the rest above sort of soaking through. If so watch the exhaust sink deeper , once the whole lot has sponged it up it will stop " sinking "
You pays your money !

 

[jrudge]

+1 for fouling. When was the Hull last cleaned?

The Op did say it had been serviced and a drive replaced - from that Inferred it was clean as it would not be put back in dirty! I could of course be wrong.

 

[volvopaul]

Cored hull below the waterline has breached and soaked up literally tons of water.
Some water may have sodden the rest above sort of soaking through. If so watch the exhaust sink deeper , once the whole lot has sponged it up it will stop " sinking "
You pays your money !

That was exactly my very first thought and I’d say that’s exactly what’s going off with it .boats don’t get lower in the water without added displacement it’s simple maths.

 

[Bouba]

I could be very wrong, but as far as I know, Beneteau and Jeanneau use a system of tiny squares of balsa for their cored hulls. These small pieces are all coated in resin so if there is a breach only the squares directly damaged will get damp. It’s not supposed to spread

 

[Whitelighter]

I could be very wrong, but as far as I know, Beneteau and Jeanneau use a system of tiny squares of cork for their cored hulls. These small pieces are all coated in resin so if there is a breach only the squares directly damaged will get damp. It’s not supposed to spread

Dont let fact get in the way of a good story

 

[BruceK]

Dont let fact get in the way of a good story

The first time I put my tub on the hard I noticed a bung plug on the back of the transom. My bilge was bone dry, but I took it out anyway. Water came out of it for 20 minutes. Closer inspection revealed the engine room floor was not the hull. There was a small 3 inch gap under all of it that connected via various limber holes between all the ribs and bulkheads. I started tracing it all back and found numerous small pools of water trapped between ribs and stringer beams where limber holes had blocked or simply absent. Alarmed I traced it all back to a radar arch leak that was catching all the water running off the top deck, down the side deck and then thanks to the canopy fastenings down the radar arch joint. Such a slow process that you didnt notice the boat slowly filling but it did. And in a way that trapped water from getting to the bilge centers and being pumped out.
There was another leak from the shower drain elbow joint that had also over time leaked a fair amount of water into a trapped space. This because the angle to the showerbox was slightly uphill from the elbow when the boat was at rest.

Two very minor issues easily resolved with a bit of corrective maintenance and subsequent years the bilge remained dry.

So cored hull disasters aside, first check for the easy outs.

 

[burgundyben]

Dont let fact get in the way of a good story

Quite.

Brochure says infused, but does not says if core, could be monolithic, where core or what core material (balsa or foam) which all has a bearing on whether water ingress into the hull is even possible.

 

[Bouba]

Quite.

Brochure says infused, but does not says if core, could be monolithic, where core or what core material (balsa or foam) which all has a bearing on whether water ingress into the hull is even possible.

Yeah, I meant balsa (not cork) désolé

 

[[2068]]

If it’s anything like my boat, the engine bay liner isn’t actually the bottom of the boat, A faulty trim tab mounting meant I ended up with quite a large amount of water in the void before the pumps kicked in.

I’d be surprised if a cored hull could soak up water that quickly.

 

[Deleted User YDKXO]

With respect to all the fanciful notions on this thread, you seem to be comparing the starboard side to the port side and without seeing a photo of the starboard side this year it is difficult to make comparisons because many boats exhibit a slight list to one side or another because of equipment location

As for the water saturation of the balsa core theory a quick back of a fag packet calculation should dispel that one. Assuming a water line length of say 15m and a beam of 4.5m and a hull thickness of 25mm you’ve got about 1.7 cu.m of GRP to saturate. Assuming 50% saturation (which is a helluva lot) that’s about 850kg of extra weight which is not enough to cause a 56ft boat to sit appreciably lower in the water. In any case, a quick lift and inspection by a surveyor with a moisture meter will confirm whether or not there is any abnormal increase in moisture content

IMHO you should lift the boat, check the moisture content in the hull, clean the hull and stern gear and then recheck the speed because the first question to be asked is how long since the hull and stern gear were cleaned?