Blue Angel (Canados 70s) Rebuild thread

[MapisM]

What does the forum think, any advice is welcome

Bart, since you asked for ANY advice...
I guess mine could appear as something which didn't take me a lot of effort, but I actually thought carefully about the possible alternatives.
And I tried to look at that from the perspective of both the owner of the boat, and also of a diver.
Bottom line, in your boots I'd leave it as it is, for the following reasons.

1) No matter how much money you're willing to spend, you'll never get a clean job anywhere near those of the other pics, because those boats are designed very differently, to start with (thickness and angle of the transom).
Frankly, I don't buy the idea that someone can make a great job just because he knows the boat very well and has worked in the yard which built the boat. In a sense, I would rather use that man just as a consultant to highlight all the potential problems of the modifications you have in mind, but without giving him any hope to get the job, if you see what I mean...

2) ...in fact, I'm willing to bet that there's some structural function in the thick GRP border above the steel rub rail. I mean, why didn't they cut the two transom doors further down, to make them level with the cockpit floor? That would have been much more convenient also on stbd side, for the passerelle access. And they could have cut also the rub rail, attaching it to the doors to make it look continuous when they are closed.
Instead, they kept a rather substantial border above the line where the deck is bonded with the hull, with a continuous steel rail all around that. There must be a reason, imho. Which is something only the boat designer (rather than the workers which actually built it) could confirm or deny.
Of course, I'm not saying that if you cut those parts the whole stern will fall apart, but I wouldn't take any chance to make it weaker, anyway. It's not that easy to strenghten all that again after you'll have cut it, you know!

3) To my eyes, the existing access to the platform is not bad at all, even for a diver with gear. As you surely know, it's much more difficult to return onboard from the water, climbing a ladder which typically is much worse that the one we're talking about: less large, less solid, and with shorter handrails - not to mention when some waves are bumping you around.
I mean, once a diver is returned from the surface to the swim platform, reaching the cockpit with the ladder you already have is a piece of cake in comparison. The only thing which your ladder doesn't allow is climbing it with your fins on (which is allowed by the ladders with a central pillar, often used on diving boats), but I don't think that should be a problem, because a) unless you have such type of ladder from the swim platform to the water, you must remove the fins already in the water, anyway; b) putting/removing fins on the swim platform should be reasonably easy even if it isn't so large, and c) also with the "newer style" molded stair, it would be very unpractical to reach the cockpit with the fins on.

4) Talking of resale value,TBH I think that you wouldn't recover one penny of such job. Actually, if the job wouldn't appear well integrated with the rest of the boat (as I fear it could be), or in the worst case, if it would negatively affect the structural strength, the boat could become extremely hard to sell.

All that said, I agree that if under the cockpit there's a utility room, it's a good idea to have a direct access from the swim platform.
But that shouldn't be too difficult, if seen as a separate issue from the stair/ladder: just open a hole in the middle of the transom (again, NOT cutting the hull/deck bonding) and stick a watertight door into it. Judging by the pics, it should be possible to use a flat door, possibly fitting a GRP groove on top of it, aligned with the existing one which runs across the whole hull.

I would also consider a larger swim platform. BTW, that IS indeed an upgrade which would make the boat more appealing and re-saleable, because that's something everyone expect these days, particularly on a boat as big as BA. I'd use the KIS principle also on that, though: just a fixed GRP extension, without the complications and weight of hi/low mechanisms. The cruising asset of BA is too nice to spoil it with some heavy mechanisms in the worst possible place for a planing boat...

 

[Divemaster1]

Simple and back to basics

Bart, as a fellow diver and boat owner, I have to go back to basics before understanding your thought process (ignoring cosmetics):

1) What is the purpose of the new steps?.... getting down to the swim platform, into the water and out ... or getting into the tender ?

2) Are you planning to change swim platform at some stage ? ... and to what extent ?.... you can get full swing/lift from water level to deck level (which could support divers & kit on platform) if you do it rigth?

If you are considering to do anything with the platform (2), I would seriously re-consider what I was going to do, until such time I understood what impact 2 would have to avoid expensive re-work.

If I were to change the platform, but wanted to replace ladder with steps, I would make up a temporary, but simple detachable GRP step with curve/angle port to starboard as a temporary measure (avoiding to ruin the beautiful lines of the boat and aft deck space...which is used when mooring)... Remember your average boat (an I include 70' in this) cannot afford making steps wide/long enough, with the hand supports you require for tired divers in wetsuits + onto a 60 Cm wide swim platform.

So to make proper, straight out, fit for purpose steps, you need a swim platform 1.5 M + ... if not closer to 2M... and I'd still consider a curve....with proper handrails ... (and your compromise step solution to original platform may have to be re-made)

If you want t get divers straight onboard, then you need a substantial ladder from platform down 1.5M as well ... your traditional diver ladder detachable would be preferrable, but additional stuff to stow away ... but clients would prefer this after a long dive, rather than something that loos "fancy".... or even better, get them lifted between sea level to deck level by electro hydraulics....

All IMHO of course...

 

[BartW]

@ MapisM

- Some serious thinking to be done about the GRP steps,
Most important condition is the stability of the stern section of the boat,
I have been confirmed from 2 individual sources that this is no problem, but will check this again.
There could be other reasons then structural function for this GRP border in the transom opening,
Fe the transom door above the ladder can not turn outside because of the guardrails along the ladder, so it must turn inside,
so this door can’t be down till the dek floor. (look at pic 4&5 in post #1) because of the transom agle, the door could not turn.

-I am really keen on a high lo platform, addition to the existing 0.6m wide platform
Your argument on boat behavior is a very important one, but the only one that could convince me not to do it. So I need to investigate this, how ?
Or make the platform as lightweight as possible? (not compromising strength)

@ Divemaster and Vassillis

I don’t believe in a one single big high lo platform that goes up to deck level, why not ?
Its very unlikely that all divers (8) arrive at the same time back from their dive, either directly to the boat or with the tender,
I don’t see me raising the platform with 2 or 4 divers, while some other divers are arriving near the boat.
Similar with swimmers, I don’t want to raise the platform up to deck level while other swimmers are underneath,
My idea about the hi lo platform is that it is an addition, behind the existing 0,6m fixed platform. Just like the example, jfm first pic in post #15
Moreover, the engine exhausts are integrated with the fixed platform, so I would need some very good reasons to modify all that.

The hi-lo platform is used :
-For swimmers, having a surface just under sea level , to play on,
-For divers get more easy in and out the tender, with the platform just above the water
-For divers to get more easy out of water, with or without dive ladder
-Quick recovery of a tender in bad sea state

So @ Alf,
the GRP steps could perfectly fit together with my idea of existing fix + hi lo platform,
I agree that the existing ladder can also do the job
But The purpose of the GRP steps is that anybody can easily “step” on to the platform,
Now you have to “Climb” a ladder.

thank you all for questioning this substantial project !

 

[Divemaster1]

Bart, understand what you are saying, but I still would consider these guys and their linear drives .. http://www.h-btechnics.com/en/produkte.htm#

... it could also open up for some additional charter possibilities..... not readily available everywhere for people with restricted mobility....

 

[BartW]

Bart, understand what you are saying, but I still would consider these guys and their linear drives .. http://www.h-btechnics.com/en/produkte.htm#

... it could also open up for some additional charter possibilities..... not readily available everywhere for people with restricted mobility....

thats what we had in mind,
met the guy's in Dusseldorf this year
not sure though wich model is the best for us,
also oem supplier ao to Fairline

 

[BartW]

you could have a beautiful teak stepped stainless steel laddrer from the gate down to the platform.

After all these interesting and valid reactions from several mates
Im considering this idea now more seriously

 

[jfm]

Bart my platform on the s78 is hb-technics and after 1 season of use I can say that it has performed perfectly. Top quality engineering and highly recommended. They are oem suppliers to several builders and they probably have 1000+ units installed, so they have figured out how to do it by now

I like the fact there is a mechanical lock in the up position so the hydraulics do not hold the platform in the UP position. The mechanical lock operates automatically via 2 small hydraulic actuator cylinders. It is a clever design and not affected by barnacles and weed

 

[BartW]

after having done some scratch work with big teak steps,
here is one of the droodles I made,

I still believe that a nicer job could be done with GRP steps.
even with the transom angle slightly bigger, this example here is very close to how BA could look like,

So a serious investigation of the Stern / transom build structure is due right now.

 

[vas]

after having done some scratch work with big teak steps,
here is one of the droodles I made,

I still believe that a nicer job could be done with GRP steps.
even with the transom angle slightly bigger, this example here is very close to how BA could look like,

So a serious investigation of the Stern / transom build structure is due right now.

I agree on the GRP steps, however I do share the concerns of the others as it's highly unlikely all this GRP there is just to add weight. FEA results done in the factory should reveal the stresses taken by this bit of transom and how to re-introduce the missing rigidity once cut out.

Furthermore, you're opting for 4 risers instead of the now 5. Care to check the height please (or just tell us the exact height from platform teak to aft deck teak), maybe steps will be too steep for your tired divers to negotiate?
Along the same lines, in order to reduce the weak zone introduced in this "operation" would be nice to design it so that:

1st step (from platform) is prodruding
2nd step is ending flush with the transom
rest 2 steps (so total 5 risers) will be carved into the transom. So in effect you only cut half or a bit more of the whole staircase vertical height leaving the bottom of the transom intact and loadbearing (where stresses are most likely higher)

l8r

V.

 

[Deleted User YDKXO]

after having done some scratch work with big teak steps,
here is one of the droodles I made,

As I said in my previous post, personally I would curve the steps through 90deg so you are stepping onto the platform not straight into the sea. For sure, grp steps would look more integrated but as has already been said, you need to be sure that you retain the structural integrity of the transom. If you really are up for throwing money at this, why don't you engage a naval architect to do the design?

 

[MapisM]

If you really are up for throwing money at this, why don't you engage a naval architect to do the design?

Naah, you wouldn't really trust a naval architect to do a better job than this forum, would you...?

 

[Deleted User YDKXO]

Naah, you wouldn't really trust a naval architect to do a better job than this forum, would you...?

Yeah you're right. Far better to have a bunch of untrained armchair boat designers that a naval architect with years of experience

 

[MapisM]

Oi, speak for yourself. I have indeed decades (rather than just years) of experience with my armchair!

 

[newWave]

Another shot at the design
1) How about the following (green is the proposition)
A gentle slope to the risers and the last large step is actually a fold down bathing platform to help the divers in/out of the water.
Shift the design somewhat and the mini-bathing platform could actually be submerged for easier access.
The stairs could be added to a center tube as to allow the use of flippers.

2) If you want an integral stair without risking structural integrity, you could have a moulding made that actually extends the length of BA and is mounted onto the bathing platform.
As this would not have to be exceptionally strong, wheight might be within reason.

 

[vas]

Yeah you're right. Far better to have a bunch of untrained armchair boat designers that a naval architect with years of experience

would really like to know what is a naval architect and what are his/her qualifications. I'm not questioning what you're saying Mike, just the very very few I know are just architects gone wrong or got an oportunity to work for the rich and make lots and have to stand them rich ppl as a compensation...
The others I could think of are the aeronautical engineers that cannot be bothered and are not qualified for such stuff.

I'd tend to agree that (on the grounds that structurally the operation is safe - which I slightly doubt...) the combined knowledge of the you, jfm, mm, am, and a few more involved with these things for 1-2 decades are way better (not to mention slightly cheaper as well)

cheers

V.

 

[jfm]

I still believe that a nicer job could be done with GRP steps.
even with the transom angle slightly bigger, this example here is very close to how BA could look like,

Bart if you decide to go for the "cut transom out" solution I think that Alalunga picture above is what you should aim for. Notice how the angle of the stairs is shallower than the transom angle. The bottom step has a teak lip sticking out aft of the transom, whereas the top step is forward of the transom face. Note also the slight angle in the risers, which I recommended above. @Vitruvas, I know this makes the steps harder to walk down, but there has to be some trickery to make all this work and angling the risers is a price worth paying imho

Bart, your photoshop picture is "wrong" because your top red step is not needed. You already have a deck there!

You need to decide the number of risers. I suggest 4. So long as the riser is maximum 275mm you will be ok. 275mm is tall for a house, but it is common to have 275 on a boat, even 325 is common on boats. Then make the bottom step stick out slightly, like Alalunga, and make the top step sdet forward, and cut into your deck (you will need to make triangular jambs to mount your gate on). It will then look like this, roughly

and

I do not agree at all the structural worries made by MapisM above. GRP is a simple material and if you cut the transom out then fit strongly moulded steps with the correct GRP procedures it will be perfectly fine. GRP is a really easy material to work with and there is no rocket science in this project. You can add 50kg to the layup if you want to make it stronger than it needs to be, and you will not notice the 50kg. Just follow the correct prep procedures etc, which your teamboss guy presumably knows about

HOWEVER, I think the transom cut is a huge job for quite small benefit. As I said above I think you would be much better with an up/down platform for ~= same cost, and a "plant on" external staricase. If you make the staircase really nice, superyacht style, it will look great. 70mm dia tube, LED downlights under each step, thick teak steps like Sq78 aft deck stairs, and a nice handrail. And, IMHO keep it straight, not curved. Something like the sketches and CAD below

 

[Hurricane]

I agree with jfm
After all the work of moulding steps/stairs and you've still only got a small bathing platform.
I think I would rather spend the money on a hydraulic bathing platform and use the existing steps.
This way you get something really useful for your diving.
Then as a second priority better steps - I like jfm's idea of thick steps and downlighters. And the steps can then use much more space and could then encroach on the whole of the existing bathing platform.

 

[MapisM]

I do not agree at all the structural worries made by MapisM above. GRP is a simple material and if you cut the transom out then fit strongly moulded steps with the correct GRP procedures it will be perfectly fine.

Well J, you're actually agreeing with my worries, if I read between the lines.
In fact, you're bringing strongly moulded steps and correct GRP procedures in the picture - in other words, some attention to the structural implications of cutting an otherwise continuous stern, and the thickest part of the deck above it.
Which is fine, I agree it's not rocket science and can be done. Ok, I also said that I wouldn't do it, but just because the current solution is already good enough - and that's imho, anyway.

Incidentally, talking of structures, what could be in your opinion the answer to my previous question - i.e. the reason why they kept that apparently pointless thick border along the deck, just above the bonding with the hull?
Bart mentioned the door interfering with the deck floor when opening, but that could have been easily fixed by eccentric hinges or some other trick, as I'm sure you know.
That was the main thing which made me think that the structural integrity is not a trivial point in this project.

Anyway, back to the possible alternatives.
IF Bart really wants a better stair, I agree that your last proposal (straight "plant-on" stair) is the best compromise.
The only thing which is tricky from a functional standpoint is the first step down from the deck, because (as your side drawing shows perfectly), it necessarily has a width/angle which is not consistent with the other steps.
And instinctively, you don't expect that in a stair, particularly a straight one.
A slight teak "prolongation" of the deck would "equalise" all steps, but it would stick out also with the door closed...
Mmm... maybe a mechanism where, while opening the transom door, the first step slides out, would be too much?

PS: on 2nd thought, maybe it's not so obvious what I meant with my previous comment on the first step.
I drew a couple of lines on jfm's drawing to explain that: it's the difference between the green and the red part of the stair which I was talking about.

 

[jfm]

Well J, you're actually agreeing with my worries, if I read between the lines.
In fact, you're bringing strongly moulded steps and correct GRP procedures in the picture - in other words, some attention to the structural implications of cutting an otherwise continuous stern, and the thickest part of the deck above it.
Which is fine, I agree it's not rocket science and can be done. Ok, I also said that I wouldn't do it, but just because the current solution is already good enough - and that's imho, anyway.

Incidentally, talking of structures, what could be in your opinion the answer to my previous question - i.e. the reason why they kept that apparently pointless thick border along the deck, just above the bonding with the hull?
Bart mentioned the door interfering with the deck floor when opening, but that could have been easily fixed by eccentric hinges or some other trick, as I'm sure you know.
That was the main thing which made me think that the structural integrity is not a trivial point in this project.

Yes I agree we're agreeing really!
I don't know why they kept that thick section, but the most likely is as Bart said - to deal with the hinge angle. The "bulwark" here is sloping inwards, on the inside, and so to make the door not hit the deck it would be necessary to have an offset hinge pin on the inside which would be ugly and a serious toe stubber. I agree that a "trick2 could be done to cure this in a better wqay, like a door opening out pantograph style but Canados seemed to prefer simple inward hinges and seemed not to be bothered with any trick (sadly!), so I think they just (slightly lazily) designed it this way. I just cannot believe there is anything important structurally in that raised part, and if there is it can be replaced with similar strength GRP material/aluminium beam after the transom is cut, if Bart decides to do that.

IF Bart really wants a better stair, I agree that your last proposal (straight "plant-on" stair) is the best compromise.
The only thing which is tricky from a functional standpoint is the first step down from the deck, because (as your side drawing shows perfectly), it necessarily has a width/angle which is not consistent with the other steps.
And instinctively, you don't expect that in a stair, particularly a straight one.
A slight teak "prolongation" of the deck would "equalise" all steps, but it would stick out also with the door closed...

Yup, agreed, the first step is tricky. If I were doing it I might be happy with a "prolongation" of the deck, and I might not care that it sticks out, but I'd want to stand on the boat to decide finally, as you would I am sure. (Actually I have been on the boat in antibes, but I do not remember this detail well enough). Another alternative is to cut out a rectangle of transom say 275 high and 400 wide and create a "backward angle" just below the gate in GRP, so that the top stair would move forward 125mm more than shown in my sketch. This would not impact the boat's structure at all (the raised part you mention would survive untouched) and would also move the whole staircase forward 125mm, so creating more bathing platform space. In fact, I like this idea very much - good inspiration MapisM Picture below of this "indentation" before the stair assembly is fitted. Come to think of it, cutting this indentation into the transom is probably less work than cutting out the GRP raised part that you noticed, and extending the teak deck, and filling the gap at the bottom of the gate. The SS tube/wooden stairs interface is more tricky because the tube must kinda pass through the wooden stairs (at the forward edge - see my CAD rendering above, only moreso) but that is do-able

Mmm... maybe a mechanism where, while opening the transom door, the first step slides out, would be too much?

Nooooooooo MapisM!

 

[BartW]

what a wealth of info on here, thank you all so much,

I'm at the boat right now, and I am very pleased to confirm that there is NO structural problem to make the integrated GRP steps,
I believe we can make that conclusion even without a naval architect,
more détailed info and pictures on that later (just returned from the restaurant with wine and all that....)

Bart, your photoshop picture is "wrong" because your top red step is not needed. You already have a deck there!

I have drawn the upper step " IN " the transom, to indicate that this was the deck level, so that this is not a real step, I was not wrong, my drawing was not clear.....at least in my mind it was correct.



I have to admidd that I used your galley stairs as an example of my SS external stairs in that droodle drawing,
and my droodle is more or less the same as your drawing ,look at the grey line in my drawing, it stops just underneath the upper outside step.
This external SS step is a potential solution, But adding a gardrail makes it look Untidy IMHO.

I took all dimensions, so I can make a drawing as it is right now, and add steps with accurate dimensions.
The steps like the Alalunga, my original idea have my preference,
perfectly illustrated in your scetch
and as you say, no big deal for a experienced GRP producer.

Thank you so much for the drawings and the idea's,
will consider all mates idea's again when I'm sober
will come back with more pictures and a " in situ" drawing soon.
drive back home tomorrow morning.

will also post pictures of the patern and the frame for the FB cover which is made here today