Hard Top for Blue Angel (Canados 70s)

[jfm]

In the initial drawing the width of the sides is only 300mm (instead of 500mm as mentioned by Jfm)
but I agree we need to make this really strong, and think carefully about the layup and profile of that section

Ah, ok. I couldn't read it well.
I think 300 might be too skinny. I know you want sun, but 500 is ok and arguably look more in proportion. Mine at 500 are skinnier than many/most other brands. If you did 500mm you would be pretty much best in class as regards getting a big opening and 500 gives you much more strength than 300 (work out the weight of 150mm of snow...)

This is 500mm...

In contrast I think Dominator got these a bit too wide on their 80 footer - see here http://www.dominatoryachts.com/en/dominator-800/exterior-photos.html

Are you using the Makefast mechanism?

 

[BartW]

In contrast I think Dominator got these a bit too wide on their 80 footer - see here http://www.dominatoryachts.com/en/dominator-800/exterior-photos.html

Are you using the Makefast mechanism?

yes, the dominator is wider than 50mm but looks OK overall, quite nice actually...
only from the under side it looks rather bulky...

yes its MF I'm considering, looks good on all aspects..., nothing ordered so far

 

[BartW]

If you did 500mm you would be pretty much best in class as regards getting a big opening and 500 gives you much more strength than 300 (work out the weight of 150mm of snow...)

100mm snow is approx 20kg/m2, so on 24m2 this 480kg, that is about 240 on each side left and right,
so to get a subjective feeling about the required strength; one person needs to be able to sit on top of one side without the frame noticeably bending.... ?

I have seen using aluminium profiles feathered in in long GRP overhangs (SQ78 FB over cockpit overhang ? )
how about integrating a alum tube in the side profiles fe 120mm x 60 mm cross section 3mm skin thickness
we can calculate the beding of such a profile

 

[MapisM]

B, fwiw I share Vas & jfm concerns about the structure flexing.
And I'd be very careful when using those side "walls" of the f/b as a basis for the front poles.
In fact, I remember that they are very solidly built, as you say, but there's a huge difference between feeling their strength by sitting on them and/or trying to flex them by hand vs. attaching a pole in a specific point where all the force components are transmitted.
I definitely would at least spread the load by building a inverse "U" steel plate to be attached on the top of those walls, and use it as a basis for the poles.

Another thought that's popping to my mind is that when the job will be completed, you might wish to have the stabs re-tuned (unless they are self-adjusting/learning, which might well be the case, but I'm not sure), because the roll period is bound to increase a bit with the additional weight up there.
Btw, that's actually a good thing, because the longer the roll period, the more effective the stabilization, AOTBE.

 

[BartW]

Another thought that's popping to my mind is that when the job will be completed, you might wish to have the stabs re-tuned (unless they are self-adjusting/learning, which might well be the case, but I'm not sure), because the roll period is bound to increase a bit with the additional weight up there.
Btw, that's actually a good thing, because the longer the roll period, the more effective the stabilization, AOTBE.

yes good idea, should asc AC if settings need to be adjusted,
we could simulate this in a test, anchored in a bay exposed to the open sea with a regular and constant swell,
feel and look at the difference in stabilising, with the tender and guests upstairs on the FB and then test with the tender and te guests off

 

[BartW]

here is another drawing,

I'm not sure if it is noteable that there are 2 poles on each side (total 4)
actually some of the hardtops in this size range I found on the interweb, have 4 poles or more,

the design is better without the two middle pillars in the drawing above,
but it would give us a lot more strength and stiffness of the total construction
a very usefull compromise !

I try-ed a few other drawings with the poles placed in an angle,
or twin poles, etc..
but none of them was better (so far)

 

[benjenbav]

That's a handsome boat which imho will look even better with that contrasting colour hardtop.

 

[BartW]

here is a first attempt / drawing for the sides cross section,
pls don't shoot me, I have no idea if this is a good way to make this,
no sizes yet, just the basic principle
all advice is welcome !

the lower side panel, is intentionally angled,
lights to be placed in that panel are aimed towards the flybridge

Oh and I forgot to indicate the 3 tubes for the wiring

 

[jfm]

Looks good. Suggest delete mould 3. Put a return lip on mould 1, right of picture, with groove for luff track and a 6mm set back for "ceiling panel". Put a return on rhs of mould 1 with same setback. Then teplace mould 3 with plastic plywood ceiling panels covered in white vinyl.
Just an idea!

 

[P4Paul]

here is a first attempt / drawing for the sides cross section,
pls don't shoot me, I have no idea if this is a good way to make this,
no sizes yet, just the basic principle
all advice is welcome !

the lower side panel, is intentionally angled,
lights to be placed in that panel are aimed towards the flybridge

Oh and I forgot to indicate the 3 tubes for the wiring

Need to give it some thought in the morning but like John has already suggested, I would remove moulding 3 and use a trim panel covered in a vinyl or fabric to give differentiation/contrast.

Personally I would look to incorporate the ribs into moulding 2 along-with a short return or shelf (on the inner edge) to receive the infill (trim). I think I would also want to return moulding 1 from the outer edge to behind the infill (trim) panel to provide the opposite shelf plus it would take all raw edges out of sight.

With shape in the inner moulding you may be able to get away with coremat rather than foam in some areas which would let you get the overall size down. What depth will the soft roof elements require? No point building a wafer thin roof if the canvas roof structure requires 500mm to sit in!

Not the easiest of things to explain, if I have chance over the weekend I will try and sketch something and send you. Can't promise, it's 6nations rugby back to back tomorrow followed by London Irish playing at 7:00pm in the evening, if England and London Irish win, don't expect anything that makes any sense from me till at least Monday!

 

[BartW]

Then teplace mould 3 with plastic plywood ceiling panels covered in white vinyl.

I was thinking if mould 3 or a panel is glued with epoxy on the ribs, so that it is all one piece , this adds a lot on the total strength of the assembly, ?

what is plastic plywood, is that plywood with a plastic finish toplayer ?
and vynil covering, do you mean just ordinary self adhesive vynil foil,

then I rader prefer a finish of the under side, spray painted same collor as the outside gelcoat...

 

[BartW]

Not the easiest of things to explain, if I have chance over the weekend I will try and sketch something and send you. Can't promise, it's 6nations rugby back to back tomorrow followed by London Irish playing at 7:00pm in the evening, if England and London Irish win, don't expect anything that makes any sense from me till at least Monday!

good luck with the match, and enjoy...

would be great if you could share your idea's in a scetch, take your time we're not in a hurry,
many thanks in advance

 

[rafiki_]

Bart, have you dismissed the thought of getting a polystyrene mould milled on a 5 axis s machine? Cost of this has crashed over the past couple of years.

 

[vas]

Bart, have you dismissed the thought of getting a polystyrene mould milled on a 5 axis s machine? Cost of this has crashed over the past couple of years.

that's a smart idea P., however,

how is he going to "skin" that though? Cannot mix polyester with polystyrene, probably has to be some protecting film/paint and then epoxy and mat?
how do you get a decently smooth finish afterwards?

cheers

V.

 

[MapisM]

Wrapping?

 

[vas]

Wrapping?

P. assuming you're replying on my questions above, I doubt wrapping can be the answer as wrapping film is rather thin so needs a nice and smooth underlying layer of something which I've no idea what would be...

V.

 

[MrB]

Ah, ok. I couldn't read it well.
I think 300 might be too skinny. I know you want sun, but 500 is ok and arguably look more in proportion. Mine at 500 are skinnier than many/most other brands. If you did 500mm you would be pretty much best in class as regards getting a big opening and 500 gives you much more strength than 300 (work out the weight of 150mm of snow...)

This is 500mm...

In contrast I think Dominator got these a bit too wide on their 80 footer - see here http://www.dominatoryachts.com/en/dominator-800/exterior-photos.html

Are you using the Makefast mechanism?

Sorry for the thread drift but is this pic (below) Match? If so, what is the hatch pictured? I cannot find this on any other 78 and cannot work out where it goes on the deck plans :ambivalence: I know you customize the hell out of your boats so it probably is or am i being a retard?? View attachment 56390

 

[petem]

It's the hatch to the custom internal flybridge stairs. Covered at length in the Match threads.

 

[MrB]

It's the hatch to the custom internal flybridge stairs. Covered at length in the Match threads.

I did think about searching the "Match" build threads but feared we would have a new change of governments before i found the answer lol. Thanks for the clarity Pete lol.:encouragement:

 

[rafiki_]

that's a smart idea P., however,

how is he going to "skin" that though? Cannot mix polyester with polystyrene, probably has to be some protecting film/paint and then epoxy and mat?
how do you get a decently smooth finish afterwards?

cheers

V.

I was suggesting cutting the mould in the polystyrene, then lay up in the normal way, gel coat then grp or carbon.