Blue Angel (Canados 70s) Rebuild thread

[jfm]

I would bet a virtual pint that 600kg of swim platform will do no harm at all to BA's ride, even that far aft. Indeed, if anything, BA could do with running a degree more bow up in any case, imho. BA's engines are very angled, so the props produce a helluvalot of stern lift

As regards a test Bart, just run with/without the weight, and use iPad or similar to tell you the running angle on a calm day. You could get a pretty good answer by just moving 7 people from midships to the aft deck, leaning right back over the aft guard rail

 

[jfm]

with rails for the tender studs, to shift the tender forward when the platform is up.

You wont need the rails Bart. The result you want happens automatically. The locus of the swim platform movement means that the tender will be about 50cm overlapped onto the fixed swim platform anyway. Hard to explain, but if you think about it you'll see what i mean...

 

[BartW]

As regards a test Bart, just run with/without the weight, and use iPad or similar to tell you the running angle on a calm day. You could get a pretty good answer by just moving 7 people from midships to the aft deck, leaning right back over the aft guard rail

good advice !
will asc 7 or 8 mates to take position (carefully) on the platform, while cruising

 

[BartW]

You wont need the rails Bart. The result you want happens automatically. The locus of the swim platform movement means that the tender will be about 50cm overlapped onto the fixed swim platform anyway. Hard to explain, but if you think about it you'll see what i mean...

OK,I get it,
thats perfect !

 

[BartW]

Last Monday, we were on the boat to make a pattern for the FB cover.
My mate has made some curved, foldable supporting tubes in advance,
He made them a little too long, and made them fitting perfectly on the boat
The pattern is made only half size, and checked the symmetry of the boat.

You can see the line on the pattern where the helm position door will come.
The pattern part to cover the window is missing on the pic, but was obviously made as well.

Then pics without the pattern

Cover will be made in 4 parts, connected with zippers. (along the tubes)
Cover will be fixed on the sides and on the rear with straps, and with small ribbons on the tubes.
The tubes are fixed with small fittings, In summer I can unscrew these fittings when they are enoying.
There is one longitudal belt, holding the tubes in place, and acts as a extra support for the cover.



Have you noticed the surrounding background ?
BA has the best spot in the harbor,
at evening with the Christmas lightning and decoration, just wonderfull
will make some pics at newyears evening

 

[jfm]

OK,I get it,
thats perfect !

Goodo!

In case i haven't explained well to anyone following this, here is the trick. When you have installed the swim platform, you lower it to a level where the outer edge (rubbing strip) of your rib, when sitting on the chocks, is just kissing the aft edge of your OLD swim platform. That is the position of the RIB, and where you place the chocks. As the platform lifts another 750mm to the fully "up" position the tender and platform nicely move forward (closer to BA's trnasom) by ~500mm. QED!

 

[MapisM]

I would bet a virtual pint that 600kg of swim platform will do no harm at all to BA's ride, even that far aft. Indeed, if anything, BA could do with running a degree more bow up in any case, imho.

Each to their own, but I wouldn't trade a degree for the hi/low platform!
The other thing is trying to understand if the boat struggles more to get on the plane.
But considering that BA performs nicely also as a skiboat, probably that won't be an issue...

 

[jfm]

Each to their own, but I wouldn't trade a degree for the hi/low platform!

But it depends on the start point doesn't it? BA has loads of "degrees in reserve". She runs very flat, arguably too flat. She looks to me like she would be improved by 1 degree of bow lift. She certainly wouldn't ride bow high if the bow lifted 1 degree. The engines really do point downwards MapisM in those Canados 70s, thus lifting the aft end up

also, i gotta say, i love the up/down platform. Easily the easiest way to handle a 400kg tender, great for swimming and playing, and i suppose good as a MOB device

 

[MapisM]

She runs very flat, arguably too flat. She looks to me like she would be improved by 1 degree of bow lift. She certainly wouldn't ride bow high if the bow lifted 1 degree. The engines really do point downwards MapisM in those Canados 70s, thus lifting the aft end up

also, i gotta say, i love the up/down platform. Easily the easiest way to handle a 400kg tender, great for swimming and playing, and i suppose good as a MOB device

Mmm... In my books, there's no such thing as a too flat planing hull.
Even the old argument that a bow high attitude is better in high following seas, that's something I never bought: no "bow high" hull can perform any better than a sensible helmsman, in those conditions.
What bow high actually means is poor stern lift, which is always a symptom of low hull efficiency, nothing else.

And re. the shafts angle, well, of course it's bound to be higher if compared to semi-tunnel hulls, but that's a basic design choice.
Anyway, even assuming that it's unusually high also for a flat V hull (but is it, really? I can't remember to have seen a pic of BA bottom), that would be an argument in favour of a flat ride, not the other way round.
If the boat would loose some stern lift (due frinstance to additional weight astern, very far from CoG, as in the case we're talking about), the vectorial result of thrust would become even worse. Or am I missing something?

On the matter of hydraulic platform, yep, I can see why you (and many others) like it.
It's indeed appealing in some respects - btw, you forgot to mention that it can also stabilise slightly the rolling at anchor, with no need for stabs+genset.
But for diving, I can't help thinking that it's useless at best, and dangerous at worst. In fact, I've yet to find ANY professional diving boat fitted with it.
Not even those which have a Jacuzzi onboard...

 

[BartW]

Mmm... In my books, there's no such thing as a too flat planing hull.
Even the old argument that a bow high attitude is better in high following seas, that's something I never bought: no "bow high" hull can perform any better than a sensible helmsman, in those conditions.
What bow high actually means is poor stern lift, which is always a symptom of low hull efficiency, nothing else.

And re. the shafts angle, well, of course it's bound to be higher if compared to semi-tunnel hulls, but that's a basic design choice.
Anyway, even assuming that it's unusually high also for a flat V hull (but is it, really? I can't remember to have seen a pic of BA bottom), that would be an argument in favour of a flat ride, not the other way round.
If the boat would loose some stern lift (due frinstance to additional weight astern, very far from CoG, as in the case we're talking about), the vectorial result of thrust would become even worse. Or am I missing something?

I like the way BA behaves, and I don’t like any more bow high, unless a small bit, one degree...
With a tiny bit of trimflaps down, I get a tiny bit more RPM, it is experience from the previous captain. (I usually don't use the flaps as one cylinder leaks oil)
but this proves to me (?) that I don’t need more bow high (efficiency wise ?)

We will certainly test her behavior with ballast on the platform, as this might require a bit more trim for best efficiency (?)

here are some picture from BA on which you can see her bottom.
I’ve always’s been impressed how much more volume she has below water level, astern compared to the bow, perhaps that’s typical on her hull design ?

On the matter of hydraulic platform, yep…….
But for diving, I can't help thinking that it's useless at best, and dangerous at worst. In fact, I've yet to find ANY professional diving boat fitted with it.

What do you mean by a professional diving boat ?

Actually I have seen some with a hydraulic platform, or a lift, or a crane

- Dive center La sirena Estartis have dive boats with a lift.
http://www.la-sirena.net/islas-meda...slands/005-diving-boats/001-diving-boats.html

- This professional dive boat has a crane
http://www.fourcault.be/
(interesting testimonial on stabilizers on there)

- Or this SQ78 for divers in SOF has a hi-lo platform,
but this is private, no charter.

Anyway, the diving is absolutely not the main reason for the platform, but I believe it can have some usage for divers as well, when carefully operated.
F.e. quick recovery of the tender.

 

[rafiki_]

Yes I agree that the cost of this GRP stair (17k) is substantial and for many mates on here not worth the benefit.
But when you know that it is less then our mooring cost from the last 5 months, and that our first season on BA we used >20.000liter diesel (since june) puts this cost more in to perspective.
And just for the affirmation, its my own money earned with honest and hard work.

about the collour matching,
this bulwark is made from wood, inside aswell as outside, so this is painted, and already now the collours don't match,
as we have to redo the painting of this upper part (not urgent) , it might be a good occasion to paint the complete hull with polyester paint, as the old GRP also looks dull,
polishing might be good also,...
but again this is not urgent.

thanks for taking time to post your comments !

Bart, I apologise if you felt that I was questioning your wisdom, or your right to spend your money on BA. I spend what I want to on Rafiki, and thoroughly enjoy the consequences.

However, I am an engineer at heart, and therefore am steeped in the value analysis process, so am always liable to estimate the costs, then add 25% contingency. Doesn't mean I do not spend the money.

I am sure BA will look great and you will benefit from the modifications.

I like the post on your F/bridge cover. Rafiki is having a new canopy made as we speak. This will give us more options in terms of a bimini fore and aft of the radar arch, for those odd days in the UK when it is really hot. Will also give us more options in the rain too, as I am not comfortable helming with the front section of the canopy in position, as the view through the window section is not good.

Will post some pics of old and new when in position.

 

[MapisM]

I like the way BA behaves, and I don’t like any more bow high, unless a small bit, one degree...
With a tiny bit of trimflaps down, I get a tiny bit more RPM, it is experience from the previous captain. (I usually don't use the flaps as one cylinder leaks oil) but this proves to me (?) that I don’t need more bow high (efficiency wise ?)
We will certainly test her behavior with ballast on the platform, as this might require a bit more trim for best efficiency (?)

Hang on a minute Bart, what you're saying proves exactly the opposite of what jfm was predicting: if the boat performs better with some trim, it means that she's even more efficient when she's "flatter", so to speak. And in spite of the additional drag of tabs, go figure!
Not that I'm really surprised to hear that: as I said, the "bow high" attitude is just a wrong way to describe what is actually a "poor stern lift" attitude, in planing hulls.
The fact that in spite of the already flattish cruising attitude of BA (judging by your clips and pics), she still benefits from some further stern lift is a further proof of what I'm saying.
Now, of course some trim tabs would become even more important if and when you will have more weight astern, but that's just a patch of a mistake, so to speak. Much better to avoid the mistake, which was my initial point - QED!

here are some picture from BA on which you can see her bottom.
I’ve always’s been impressed how much more volume she has below water level, astern compared to the bow, perhaps that’s typical on her hull design ?

I really can't see ANYTHING unusual in BA hull shape, volumes, shafts angle, etc.
Did jfm see your engine rooom? I guess his comment was based on the fact that your engines are obviously more leaned backwards than in his boat, which has tunnels. But that's comparing apples with oranges.

What do you mean by a professional diving boat ?
Actually I have seen some with a hydraulic platform, or a lift, or a crane...

Nope, actually I was talking of boats used commercially by diving centers.
Since IIRC you've been in Maldives, you surely know that even the bigger boats (hence my reference to those with a Jacuzzi onboard...) have just very large platforms and wide, stiff ladders. Nothing else.
I very much doubt that they could even get an insurance cover, if they would use lifting platforms. They're just too dangerous.
The lifting system in "La Sirena" website is something completely different (maybe meant also to help impaired divers?), not to mention the Fourcault, which obviously has equipment designed for technical diving.
And that modified Sq78, well, ermm... let's say that it's a clear cut case of "each to their own", if I've ever seen one!
Now, having said all that, of course if you like the lifting platform regardless of its usage for diving, that's fine.
As I already said, I can see the reasons why it's increasingly popular on the latest generation boats.
But in your boots, I'd carefully simulate the weight effects first, and I'd never even think of using her for lifting divers.

PS: where was BA lifted in those pics? I like the "better safe than sorry" slings arrangement!

 

[BartW]

Bart, I apologise if you felt that I was questioning your wisdom, or your right to spend your money on BA.

no apoligies needed Rafiki, I only felt constructive advice.
My answer to your post was also supposed to be an answer to all other mates who questioned the spending.
But a warning every now and then doesn't harm, as I tend to get used to useless spendings

I like the post on your F/bridge cover. Rafiki is having a new canopy made as we speak. This will give us more options in terms of a bimini fore and aft of the radar arch, for those odd days in the UK when it is really hot. Will also give us more options in the rain too, as I am not comfortable helming with the front section of the canopy in position, as the view through the window section is not good.

Will post some pics of old and new when in position.

yes I'm curious to see that,
we had 3 custom made canopies on previous boats ( 21ft, 25ft, 29ft) from the same supplier (man in the pic)
so have some experience now, and I'm interested how others make them.

 

[BartW]

Hang on a minute Bart, what you're saying proves exactly the opposite of what jfm was predicting: if the boat performs better with some trim, it means that she's even more efficient when she's "flatter", so to speak. And in spite of the additional drag of tabs, go figure!
Not that I'm really surprised to hear that: as I said, the "bow high" attitude is just a wrong way to describe what is actually a "poor stern lift" attitude, in planing hulls.
The fact that in spite of the already flattish cruising attitude of BA (judging by your clips and pics), she still benefits from some further stern lift is a further proof of what I'm saying.
Now, of course some trim tabs would become even more important if and when you will have more weight astern, but that's just a patch of a mistake, so to speak. Much better to avoid the mistake, which was my initial point - QED!

I just gave some extra info / remarks,
to confirm that I agree with your vieuw on BA's attitude.

I really can't see ANYTHING unusual in BA hull shape, volumes, shafts angle, etc.
Did jfm see your engine rooom? I guess his comment was based on the fact that your engines are obviously more leaned backwards than in his boat, which has tunnels. But that's comparing apples with oranges.

I know very little about hull shape, volumes, schafts angle, etc
just gave some observations, but no judgement,

its for the more experienced mates like you to make conclusions or judgements from these observations.
which are very highly apreciated !

don't forget that I really welcome your info and advice, and ANY comment is taken seriously, but then taking decisions, as you know not much on owning a boat is rational

PS: where was BA lifted in those pics? I like the "better safe than sorry" slings arrangement!

that was in the Rizardi yard in Ostia, it was the liftout for the survey, GC is on one of the pics.
I have been told that the service office of the yard is closed, but don't take me on the exact details.

 

[BartW]

Nope, actually I was talking of boats used commercially by diving centers.
Since IIRC you've been in Maldives, you surely know that even the bigger boats (hence my reference to those with a Jacuzzi onboard...) have just very large platforms and wide, stiff ladders. Nothing else.

I have been on many diving dayboats and diving cruise boats all over the world, but all of them were very rational, efficiently build, no unnecessary extra's.
None of them were build in a modern yard, and all of them were build with just one important feature in mind, and that is low cost / high profitability.
So a hi lo platform does not fit in there.

Ones again, the diving is not the reason for the hi lo platform, but it might be possible to use it for that purpose, I should have asked these SQ78 guy's.

the main reasons are comfort / beach for the swimmers,
and easy recovery of the tender
remember also that the orriginal idea, the diving usage of BA has been seriously questioned.

 

[MapisM]

don't forget that I really welcome your info and advice

Glad of your appreciation!
Coming to think of it, there's another thing worth mentioning.
In those pics, trim tabs are somewhat lowered (the one on port side at least, but I guess also the other one).
I'd suggest to take as a habit to keep them fully raised, whenever the boat is not cruising.
In fact, it's better to raise them as soon as you're entering a marina, because aside from leaving them fully raised when the boat is not used, that also improves maneuverability in reverse.

 

[BartW]

In those pics, trim tabs are somewhat lowered (the one on port side at least, but I guess also the other one).
I'd suggest to take as a habit to keep them fully raised, whenever the boat is not cruising.
In fact, it's better to raise them as soon as you're entering a marina, because aside from leaving them fully raised when the boat is not used, that also improves maneuverability in reverse.

aha I expected you would notice that,
The boat was lifted the day before the survey took place , (I was not there during liftout) so I don't know why the flaps where down,
but from the moment that I own BA, the flaps are almost always raised, mainly to avoid barnacles and fouling on the cylinder shafts and indeed manouverability in reverse.
I have only used the flaps on a few occasions:
for faster on the plane, but thats not an issue,
and during long passages on flat seas, to optimise efficiency (lower fuel).
and in two occasions with strong beam wind.
but never in the fully down position

when we discovered a leak in a oil hose connection, (oil disappears quickly when I move the flaps )we stopped using them,
this can only be repaired during a liftout.
(fitting between cylindersupport and hose inside the hull skin is leaking )

 

[MapisM]

 

[Deleted User YDKXO]

I like the way BA behaves, and I don’t like any more bow high, unless a small bit, one degree...
With a tiny bit of trimflaps down, I get a tiny bit more RPM, it is experience from the previous captain. (I usually don't use the flaps as one cylinder leaks oil)
but this proves to me (?) that I don’t need more bow high (efficiency wise ?)

BA can't run at just 1 deg bow high. Most planing boats plane at 4-7deg as the hull has to present a certain angle of attack to the water in order for planing to happen. It seems to be fairly typical of Italian designed boats that the hull has to be trimmed down a little to offer maximum speed but unlike Mapism, I don't see this as bad hull design because it gives the helmsman a choice of whether to run with the bow down or bow up. And IMHO it does make a difference in a following sea to be able to run with the bow raised a little. You can experiment with BA yourself in a big following sea but I have found with many of the boats I have owned that running with tabs down in a big following sea causes the bow to dig into the waves too much whereas with no tabs the bow rises over the waves more easily.
IMHO, with a boat as big as BA, adding the weight of a hi-lo platform won't make much difference to the overall trim of the boat but its worth ballasting the stern to find out

 

[BartW]

BA can't run at just 1 deg bow high. Most planing boats plane at 4-7deg as the hull has to present a certain angle of attack to the water in order for planing to happen.

I have the impression that BA planes flatter then Britt. Olesinski hulls, 3...5deg (just a guess)
my point was, +1deg in addition to the normal 3..5deg, caused by the extra weight from the platform.

IMHO, with a boat as big as BA, adding the weight of a hi-lo platform won't make much difference to the overall trim of the boat but its worth ballasting the stern to find out

agree

You can experiment with BA yourself in a big following sea but I have found with many of the boats I have owned that running with tabs down in a big following sea causes the bow to dig into the waves too much whereas with no tabs the bow rises over the waves more easily.

not much to experiment,
with trim flaps raised, she planes fairly flat, even at slow speed.
there is no method to make her more bow high
in case you missed it, look at this video, this was with trimflaps raised.