Q: bathing platform height above w/l ?

[vas]

another odd Q from myself...

Trying to decide on the bathing platform and I'm a bit confused on the relation between boat length and type (D or P) vs the length of the bathing platform regarding the height above w/l that the platform should be installed.

On my 43ft planning hull, a tiny bathing platform of approx. 60cm was placed around 20cm above w/l

Planning to fit a 1.2m long platform, would 20cm still be acceptable or should I go for 30cm (or even more!)?
I'd have though that they've setup a rule of thumb for that sort of thing, no?

Bear in mind that the platform will be a ss frame with ss supports to the bottom of the hull at trim tabs level covered in teak strips (25X30mm 20mm apart) So not a solid flat thing that water would be able to mess about in a dangerous way. Further strips will be placed on a bow-aft axis rather than prt-stbrd one, so less resistance through water

cheers

V.

 

[jimmy_the_builder]

another odd Q from myself...

Trying to decide on the bathing platform and I'm a bit confused on the relation between boat length and type (D or P) vs the length of the bathing platform regarding the height above w/l that the platform should be installed.

On my 43ft planning hull, a tiny bathing platform of approx. 60cm was placed around 20cm above w/l

Planning to fit a 1.2m long platform, would 20cm still be acceptable or should I go for 30cm (or even more!)?
I'd have though that they've setup a rule of thumb for that sort of thing, no?

Bear in mind that the platform will be a ss frame with ss supports to the bottom of the hull at trim tabs level covered in teak strips (25X30mm 20mm apart) So not a solid flat thing that water would be able to mess about in a dangerous way. Further strips will be placed on a bow-aft axis rather than prt-stbrd one, so less resistance through water

cheers

V.

I'd say that the closer to the waterline the better. One of things I like about the T40 bathing platform is that it is close to the waterline, which just makes it easier to get yourself back out of the water if you have an unplanned swim. Given your particular construction, it's hard to see much risk with accidental submersion of the platform as you transition to and from planing.

 

[jfm]

There's no right answer. Higher is awkward for swimming but can result in less wave slap when at anchor. Top surface 300mm above the water (looking at a piece of A4 paper as I type!) is about right imho

 

[Bertramdriver]

Hi Vas I've been through the same process myself and the Bertram swim platform is equally niggardly. I tested my idea by bolting a sheet of ply 2.44 x 1.22 m onto the existing platform. I'm glad I did.
In the end I decided to live with what I had . The deciding factors were
The 50mm SS frame plus iroko slats I planned to use added nearly 75 kilos on the back of the boat. That, plus my bespoke hydraulic Passerelle were just too much weight aft for my semi hull.
The exhausts run out below the platform and an extended platform of 1.2m trapped the exhaust fumes underneath and then curled them up the transom onto the aft deck at pootling speeds. The guests were remarkably quiet until I realised they were suffering carbon monoxide poisoning.
I mounted my test extension on top of the existing platform (about 25 cms above standing water level) When going on the plane the test plate just ripped off from water pressure from the hull wake. I reckon I would have needed at least 45cms clearance above water level to be safe.
In the end I decided that for the amount of activity around the swim platform I didn't have enough life left.
I would seriously recommend Vas, that if you want to do it, try the test plate on your swim platform first before you commit time and money to a final design. It may save you tearing a bit of your transom off.
How about an alternative thought. Extend out your hull by 1.2 metres with shaped prefabricated GRP box structure. You then get the benefit of room to uprate your exhaust system inside the box, increase storage, increase water line length and therefor pootling speed. You might even get a trim benefit.
Good luck

 

[vas]

Hi Vas I've been through the same process myself and the Bertram swim platform is equally niggardly. I tested my idea by bolting a sheet of ply 2.44 x 1.22 m onto the existing platform. I'm glad I did.
In the end I decided to live with what I had. The deciding factors were
The 50mm SS frame plus iroko slats I planned to use added nearly 75 kilos on the back of the boat. That, plus my bespoke hydraulic Passerelle were just too much weight aft for my semi hull.
The exhausts run out below the platform and an extended platform of 1.2m trapped the exhaust fumes underneath and then curled them up the transom onto the aft deck at pootling speeds. The guests were remarkably quiet until I realised they were suffering carbon monoxide poisoning.

I'm aware of the weight issue, but in theory I've got a ton less of engines due to the PO replacing the DD to some lightweight IVECOs, so I have some weight to spare so to speak.

The other big difference between the Mystere and your Bertram is that the exhausts are outside the hull, and the platform will not be blocking the fumes especially as it wont be a single slab of solid grp but a series of thin strips of teak with plenty of space in between. So less of a chance of killing the guests

I mounted my test extension on top of the existing platform (about 25 cms above standing water level) When going on the plane the test plate just ripped off from water pressure from the hull wake. I reckon I would have needed at least 45cms clearance above water level to be safe.
In the end I decided that for the amount of activity around the swim platform I didn't have enough life left.
I would seriously recommend Vas, that if you want to do it, try the test plate on your swim platform first before you commit time and money to a final design. It may save you tearing a bit of your transom off.

I understand the point, but it's quite difficult to do atm, and since the whole bathing platform will be a ss frame with the inset teak, I'll probably place it at 30-35cm above waterline and if it turns out it's too low, I'll change the brackets and lift it up next time she's out on the hard.
And actually thinking about my raw materials, the platform got to be 1.1m not 1.2 as my teak beams are 2.2 and I'm not wasting all that teak for nothing

How about an alternative thought. Extend out your hull by 1.2 metres with shaped prefabricated GRP box structure. You then get the benefit of room to uprate your exhaust system inside the box, increase storage, increase water line length and therefor pootling speed. You might even get a trim benefit.
Good luck

Jon,

I think that's way over the top even for my rebuilt standards
Didn't seem to be bow high, so I don't know what real benefit that'll have other than a few months of extra work that I don't have right now.

Mind someone should invent a hull lengthening technique for pootling at slightly higher D speeds!

cheers

V.

 

[BartW]

Vas, how about designing a DIY hilo platform ?
Not a complex folding support version, but much simpler just vertically up down model
Your transom shape allows for that,
Your family would LOVE that, Im sure.

 

[vas]

Vas, how about designing a DIY hilo platform ?
Not a complex folding support version, but much simpler just vertically up down model
Your transom shape allows for that,
Your family would LOVE that, Im sure.

OK, np, where are the sketches then Bart?
George is starting next week with the flybridge seating as per your sketches.

need something for after Easter

cheers

V.

 

[Portofino]

After selling to Ferretti in 2004 -they set up down the road XL 43 -so if you contact XL marine In Roma - they may be able to put you in contact with the fabricator ? ( newer" post Ferretti " have glassed in pods -not the same )
You set your own height -when you fix it -they will also probably advise how to fit