Boat design consultancy

[MapisM]

If it were my decision, I'd leave the current structure alone and add one or maybe two biminis for shade.

I see your point and I wouldn't disagree (also costwise!), if it weren't that the possibility to fully cover the FB with some canvas attached to the HT is also an important reason behind the HT idea.

PS: for protection of the whole FB deck when the boat is not used, as I said previously.

 

[petem]

Mapis, I assume that you've considered a solid canopy frame with a sliding canvas middle section? This might reduce weight and also allow you to open the roof when it's a bit cooler? You could even make it electric!

Pete

 

[BartW]

Yup!

Anyway, back to the matter in had. Here is another doodle. Apropos nothing really. Just food for thought!

you're almost there J, ready for the cad drawings
but perhaps I would make the side legs a little smaller.

@ MapisM, why would you make it foldable ?
I'm afraid that the construction will be difficult to make strong enough, while looking nice ?

On my boat I didn't take the hardtop option, as I like to be in the sun most of the time, but by getting older I realise this is no good.

 

[jfm]

Hoping that the patron Saint of Naval Architects will forgive me!

Hmm, and bearing in mind BJB's thoughts, you could consider the principle of adding something that deliberately looks like an addition, and doesn't "try" to blend in. A bit like "listed" ancient stone houses in UK where the planning authorities will not allow you to build an extension by copying the architecture, but adding a glass cube or pyramid like the Louvre is ok. So, see suggestions below all in 40 or 45mm s/s tube (except the "rungs" which should be smaller, 30mm or 35mm dia)

Also, this "less integrated" look is easy to remove if you change your mind (a few bolts and a re-wire) and is easier to make. And the design "includes" a ladder, so you don't need to make an extra ladder and decide where to put it. This is actually quite an economic solution compared with the others

Do you have good enough access to route the radar (etc) wires up through the 45mm s/s tubing?

2nd thoughts, perhaps move the aft legs a bit more aft, like this

Thirdly, here it is with backward facing (right brain) aft legs. This would be better support for the canvas work (sides) btw

 

[Wiggo]

Pretty good. I've taken the liberty of adjusting the angles to match the flybridge supports...

 

[BartW]

Also, this "less integrated" look is easy to remove if you change your mind (a few bolts and a re-wire) and is easier to make. And the design "includes" a ladder, so you don't need to make an extra ladder and decide where to put it. This is actually quite an economic solution compared with the others

here
http://www.atlantictowers.com/at_sub/products_fr.htm?gclid=COjR_fXn9J8CFYqD3god3Ae4YQ
available at a affordable, read "tryout", price

 

[jfm]

here
http://www.atlantictowers.com/at_sub/products_fr.htm?gclid=COjR_fXn9J8CFYqD3god3Ae4YQ
available at a affordable, read "tryout", price

That company's products could be perfect for MapisM. And they have a distributor in Italia http://www.mavimare.com/

 

[BartW]

That company's products could be perfect for MapisM. And they have a distributor in Italia http://www.mavimare.com/

when MapisM wants to go this route, it would be worth first to contact Atlantic directly, their experience could be helpfull, they have loads...

When I puchased my Radar arch 2 years ago, there was no "active" Belgium distributor. The communication directly with Atlantic was very good, and the goods where delivered well packed, and in good order as expected.
There was a comprehensive installation instructions DVD with the delivery.

after all, Sardegna is another country almost

 

[AndieMac]

AndieMac: How thick are the sheets you used, 3 or 4mm I guess?
And didn't you have any troubles with the white coating? Quite often with aluminum, whenever you must "break" the coating for any reason (e.g. for the screws used to fit the grab handles or the canvas rails), the coating begins to peel and make bubbles, which slowly propagate all around.
Besides (but this is just a curiosity), what's the reason for the hatch? From the pics, it looks like you can easily reach the HT from the FB...

The HT has been there for nearly six years, the sheet is 2.5mm with plenty of internal framed support. There is lots of fibre, nylon washers and sealant used anywhere SS comes into contact with alloy, so far so good.
The dinghy gets dragged across the roof with no special treatment, imo the powder coating is great, and cheap, $200.00 (gbp100.00?) for upright supports, HT and hatch.

The hatch can only be that size to fit within the stb. edge long sheet, we are a family of long skinny people anyway , and the forward edge of the HT overhangs the aft edge of the saloon cabin top, for maximum protection from rain, cold (nights) and heat.
Done my time balancing around narrow side decks with nothing to hang on to....

 

[MapisM]

Thanks folks, yet another lot of very useful stuff.
Following the order of your posts:

@ petem: nope, I never even considered a sliding canvas. Frankly, I think that the only boats where it makes sense are HT sportcruisers, beceuse at their helm you're always a bit "enclosed", and the sliding roof can give a more open feeling.
I've actually seen it also on the HT of some FB boats, but only on very big ones, where it's probably fitted just because in the context of multimillion boats, each and every possible gadget becomes a must have...

@ BartW: I actually used a bad wording, it' not really foldable, but with regard to the reasons... See below.
Oh, and re.getting older, wazzat? As my wife always tell me, I'm only getting better (or was it bitter?)...

@ jfm: yup, there isn't a lot of stuff up there: radome and gps mushroom, plus the aerials for vhf, meteofax and TV. One of the 45/50mm tubes should be enough. Besides, the gps cable could actually be removed. I guess it was fitted on the arch just because most installers think that the higher the better, whilst for the gps it's actually the other way round!
Good suggestions also re. the alternatives with all s/s legs. I was also thinking of improving the canvas support when I mentioned the "foldable" HT... See below.

@wiggo: wow, impressive drawing. Amazing how realistic that front tube is!

@ BartW and jfm again: thanks for the links, it's surely useful to hear some specialised guys, at least to cross-check the costs.
But I must say that in the yard where the boat is sheltered there are some guys who know their job, and can work with wood, alu, steel and grp.
Besides, in a job like this there are just too many things that must be checked on the boat, before and during the build. All the relevant measures, the better points where to attach the structure, and so on.
Nothing against more industrialised products, probably they would be both better finished and less expensive, but I think they're mostly appropriate for streamline production boats, for which the HT producer can use standard moulds.
Unless of course one can bring them the boat, but it's quite a long way to New Jersey!

@AndieMac: interesting. Makes me wonder how rarely another boat I know have been rinsed, to have the windshield alu frame that must be repainted after 3 years... But that's another story.
___________________________________
Now, back to my "right brain" idea.

But let me explain it a bit, before starting to laugh at it.
As I already mentioned, a fair share of the reasons behind this project is to make it possible to fully cover the FB.
But mind, that's just for its protection, not for helming the boat from the FB in bad weather - I never felt the need for that, even in the worse conditions, because the visibility from downstair is good enough.
Therefore, the boat would be left with the canvas attached to the HT and all around the FB sides, whenever not used.
BUT!
Having full canvas along the sides, above the console and (particularly) above the whole aft part of the FB which the HT would not cover, means an awful lot of canvas. Hence a lot of windage and pressure on the canvas itself. And a high risk of "filling" the aft part of the canvas with rain water, possibly tearing the canvas in case of strong rain.

So, I wondered how it would be possible to better exploit the HT as a FB coverage, and I thought of lowering the HT, moving it further aft at the same time. Below are the drawings of the thingie, both in the normal (raised) and in the lowered position. The radome is still missing, I had enough of PC drawings for tonight...
In my mind, the HT part should be in cored GRP, possibly with varnished wooden borders along the edge as a finishing touch, but that's not important at this stage.
The legs would all be s/s tubes, 45-50mm, attached to both the HT and the FB through bolted joints. The last tubes astern should have two joints on the FB, one for the raised and one for the lowered position.
Sort of Meccano strips - shame on jfm for making me think of that!
Probably the "main" couples (port+stbd) of tubes should be welded to a similar tube connecting them under the HT, along the beam, to grant enough lateral stiffness. Maybe with smaller strenghtening tubes welded in the upper corners, forming a triangle.

Advantages:
smaller canvas all around, less windage, less risk of tearing them;
possibility to reach the equipment above the HT, and also to clean it, without walking on it. This means that the top could be much less bulky, if compared to one built to withstand peeps walking on it;
elimination of safety concerns connected to the ladder required to climb above the HT: there's at least a couple of kids I can think of, which I could only handcuff to some rails, to keep them from climbing up there all the time...

Disadvantages:
The only one I see is the work required to lower/raise the HT, but it would be only when arriving to the boat or leaving her. Besides, when using the boat in cold seasons, the whole HT/FB could be left "closed". A line attached to the capstan of the anchor winch could take care of the weight.
I also though of using hydraulic pistons instead of the last two movable tubes astern, but I'm not sure it's worth the complication...

Ok, your turn to comment now.
But please, be kind. It took me a lot of thoughts to elaborate the idea; if it's totally stupid for some reason, please let me know, but as politely as possible!...

 

[AndieMac]

Ok, your turn to comment now.

This is truely thinking outside the square MM.........I like it

We can leave all the tricky scientific thinking to JFM

What if the aft/downward facing support legs ran along tracking similar to yachtie mainsheet tracks, that could manually lock into multiple positions. Obviously heavier duty, but simple.

On a lot smaller scale, 'Bar Crusher' alloy boats, do an above helm HT that hinges from the targe bar, to allow the HT to either seal on the upper windscreen frame, or lift up to a locked position to allow a 30cm (12in.) opening.

If the nav./com. gear is located well aft on the HT, a small domestic ladder could be used for the few occasions you may need to access this upper area. I just use an extendable 'truckies' wash broom to clean the HT on the Princess (18' x 12') and polish it (GRP) once a year.

 

[jfm]

Very nice stuff MapisM! Apart from the advantages you mention, I think it looks good - it meets the principle above of not trying to look part of the original which is good I reckon

You'd have to take care not to have wobbliness in this thing. A few engineering thoughts:

1. I think the tubework should be 50mm dia and formed as "goalposts" like a typical bimini, as you say. Else you will never get the lateral stability.
2. Where the GRP HT attaches to the crossbar of the goalpost, you should make proper (split) bearings milled from 2 lumps of (say) 50mm x 100mm x 150mm aluminium block
3. Likewise where the feet of the goalposts attach to the deck you should get some very big clevis pin units made, one to bolt to the deck and the other to weld to the s/s tube.
4. I dont think hydraulics are too much of a complication. It's dead easy to source neat 24v hydraulic packs and s/s rams. There are engineering catalogues full of them. When you get a load of red rain you'll be glad of pressing a button to clean the top of this thing. And lower it to insert the canvas into the track, etc. Only tricky part that I can see with hydraulics is how to run the hoses, out of sight. Kinda depends if you can run them across the boat, hidden above the saloon ceiling liners? In contrast, a line from the anchor winch sounds a bit of a palaver, and quite poor geomtry when the HT is lowered. You can get nice deck glands to bring the hydrualic hoses thru the deck.
5. Also consider hydraulic rack/pinions. These are a hydraulic ram say 300mm stroke, connected to a rack, and as you push the ram backwards and forwards it turns a pinion in the middle of the rack. The torque is so large it would rotate the aft goalpost to lift the HT, then you would click in the aft diagonals to make it rigid. Fairline are doing this on the (£20k) bimini for the Sq78 now, it was on the boat at LIBS, and it was a beautiful bit of engineering. I think in your case the simple rams are a better idea though; simpler and cheaper
6. You should work out the locus you want as this thing lowers. The front legs could be shorter than the aft, esp if you mount the front legs the dash. But that would mean the front edge of the HT lowers faster than the aft edge. Whether that helps you for cleaning/maintenance I dont know. You might prefer it to stay horizontal as it lowers.

This would be a great job, and look good imho, but it needs high-end engineering to make it rigid

 

[MapisM]

Very nice stuff MapisM!

Thank you! So, do you mean it could work, in the first place? That's already more than I dared to hope...
Following your numbering:
2) I'm not sure to have fully understood what you mean. The alu brick should be attached to the HT I guess (how?), with the goalpoast attached to the bearing to allow for its rotation?
3) must admit that I had to google for "clevis pin", but that's now understood. Actually that's what I already had in mind for the deck, together with a s/s plate long enough to be bolted to three beams (there's one of them every 25cm or so).
4) why aren't you considering rams with the integrated pump, in order to route up there just the 24v wiring? Do you think there aren't around some big enough for the job, or maybe that it's better to avoid them in an external application, exposed to any kind of weather? Or any other reason?
5) Nice, but I agree with your conclusion, simple rams are more appropriate here. Though I like the additional safety of clicking in the diagonal when raised. Which could actually be done also with the ram, just using a diagonal slightly longer than the extended ram and placing it parallel above the ram, to further secure the whole structure when raised. No need for that when the HT is lowered, because obviously the ram should be sized in such way that it's fully recessed when the HT is lowered.
6) Yup, actually behind my previous drawings there are already some thoughts about the geometry of the thingie. It should work nicely in parallel, with legs of the same lenghts, all bolted to the FB deck. Subject to further checks onboard, obviously.

Apropos, you wouldn't fancy a weekend in southern Sardinia, for a change towards SoF, would you?

 

[jfm]

Thank you! So, do you mean it could work, in the first place? That's already more than I dared to hope...
Following your numbering:
2) I'm not sure to have fully understood what you mean. The alu brick should be attached to the HT I guess (how?), with the goalpoast attached to the bearing to allow for its rotation?
3) must admit that I had to google for "clevis pin", but that's now understood. Actually that's what I already had in mind for the deck, together with a s/s plate long enough to be bolted to three beams (there's one of them every 25cm or so).
4) why aren't you considering rams with the integrated pump, in order to route up there just the 24v wiring? Do you think there aren't around some big enough for the job, or maybe that it's better to avoid them in an external application, exposed to any kind of weather? Or any other reason?
5) Nice, but I agree with your conclusion, simple rams are more appropriate here. Though I like the additional safety of clicking in the diagonal when raised. Which could actually be done also with the ram, just using a diagonal slightly longer than the extended ram and placing it parallel above the ram, to further secure the whole structure when raised. No need for that when the HT is lowered, because obviously the ram should be sized in such way that it's fully recessed when the HT is lowered.
6) Yup, actually behind my previous drawings there are already some thoughts about the geometry of the thingie. It should work nicely in parallel, with legs of the same lenghts, all bolted to the FB deck. Subject to further checks onboard, obviously.

Apropos, you wouldn't fancy a weekend in southern Sardinia, for a change towards SoF, would you?

Yup, sure it could work. It just raises some different engineering problems but if done well I think it would be the best (and best looking) of all the designs discussed in this thread.

2. Yep, I just meant a machined lump of ali like this sketch (or similar - it's a genral idea and could be refined). Needs to be tapping grade, so an alloy like say 6082T6 (formerly H30TF), not a "pure" ali. Point is, you can measure the OD of the s/s tube then machine the hole in the ali to make sure you have the right fit (you need a H7 or H8 fit for the hole using ISO terminology; this defines the gap between the shaft and the hole). The HT would bolt to the "saddle" part of this ali unit. (Also it would be nice to make 4 split clamp rings to stop sideways-sliding of the HT. I mean big s/s Polo Mints, 50mm hole, split into 2 semicircles, clamped together by 2 socket cap screws)

3a. The clevis pin assembly might need to machined from s/s block to get a nice job. Holes need to be reamed not drilled, to get H7 type (non rattle-y) fit. You need a workshop with lathe and milling m/c for this project. Let me know if you get stuck on this aspect becuase I or NickH can make stuff like this in UK and mail to you easily, though your boatyard may be fully equipped.

3b I'm a bit worried about aesthetics of a s/s strip 600x50x6mm on the deck. How thick is your teak planking? Would be nice to rout a 606x56mm slot in the teak and sink the s/s plate in flush, and black caulk the edges. If use s/s countersunk socket head M10 screws that might look quite nice, with mirror finish on the s/s. Or if the teak is 10mm, sink the s/s right down and glue 4mm teak veneer to the top

4. I've never seen a ram with integrated electric pump that looks nice, but then I don't surf hydraulics catalogues Do you know of one? For this sized stuff I'd doubt the pump could be small enough to look nice. But that's something to research. You could actually use a backstay/vang hydraulic ram, with a manual pump (you just crank a lever back and forth) but electric would be nicer

5. Yes, you could. Though left brain (or is it right?) says hydraulics really dont need that and are happy to take load constantly for 20 years, even dynamic loads (vangs, for example, or the p/steering rack in your car for 200,000km)

Yes ok I'll bring some spanners to Sardinia sometime . By coincidence I got a charter enquiry on the boat last night; repeat booking from 2009, very nice people. They want 3 weeks (!) which will include going right around Sardinia; I need to do some research and learn about anchorages there etc! Another thread, another day

 

[MapisM]

Wow J, this is the kind of post which makes me wonder why there are no builders (which I'm aware of, at least) using these forums to check the feasibility and appreciation of their new ideas. Many many thanks for all your support.

In which period are those 3 wks? I might be around, if it's between Jun-Sep. Anyway, I'll be more than happy to help if I can.
When it comes to anchorages, fuel, marinas, restaurants in that area, I can't say that I know all of them just because I wouldn't say that of ANY subject. But surely there aren't many I'm not aware of.

Now, back to your suggestions/questions:
3a. Understood, thanks, I'll let you know after talking with my yard;
3b. The planking is rather thick, originally 15mm - now more likely 12 or 13. But actually I would try to bolt the plates on the lateral bands if the geometry allows that (to be checked onboard). I don't know exactly how thick they are - a lot anyway, surely >1inch. They're the stronger structural parts of the FB deck. You can see them also in the previous FB pics, but you can see them even better in the pic below (they're the big varnished iroko planks surrounding the teak deck).
Those bands could surely take a fully sinked plate. I'm only wondering if we're not going too far with regard to finishing... She's just a sort of fishing wooden trawler, after all...
4. The ones I have in mind are those used e.g. for engine hatches. Not the most elegant bits, but acceptable imho. Not sure about how bigger ones would look, though (and if they exist!).
5. On second thought, I agree. Btw, even in the unlikely event of a loss in one of the rams (or even both), the HT would never crash down, but just lower veeeery slowly, I suppose. It's pointless to have an additional tube hanging around.

 

[jfm]

In which period are those 3 wks? I might be around, if it's between Jun-Sep. Anyway, I'll be more than happy to help if I can.
When it comes to anchorages, fuel, marinas, restaurants in that area, I can't say that I know all of them just because I wouldn't say that of ANY subject. But surely there aren't many I'm not aware of.

3b. The planking is rather thick, originally 15mm - now more likely 12 or 13. But actually I would try to bolt the plates on the lateral bands if the geometry allows that (to be checked onboard). I don't know exactly how thick they are - a lot anyway, surely >1inch. They're the stronger structural parts of the FB deck. You can see them also in the previous FB pics, but you can see them even better in the pic below (they're the big varnished iroko planks surrounding the teak deck).
Those bands could surely take a fully sinked plate. I'm only wondering if we're not going too far with regard to finishing... She's just a sort of fishing wooden trawler, after all...
4. The ones I have in mind are those used e.g. for engine hatches. Not the most elegant bits, but acceptable imho. Not sure about how bigger ones would look, though (and if they exist!).

First 3 weeks of August! More on this later!

3b, Ah, all ok. Yes, I think s/s plates would look fine on those varnished strips. No point in weakening the wood by cutting/routing. The aft plates ideally should be made so the HT leg attaches to the front of the plate and the hydr cylinder to the aft, of the SAME plate. Then the tension in that triangle is entirely taken by the metal not the wood. i guess you already intended that

4. I doubt engine hatch stuff will do. It tends to be a bit mickey mouse sized, though I haven't surfed any catalogs. You will be wanting much heavier stuff, like say 20mm diameter for the ram and 50mm dia for the cylinder I think

I'm wondering if you need double acting hydrualics, to avoid the wind catching it when its down. You probably do, tho it would be interesting to see how much extra that costs. Aesthetics-wise, with double acting you need to take a hydraulic pipe outside the cylinder, to fee oil to the top of the piston. That might look ok, you'll need to see the catalogs. But just for info, you can get some beautiful double acting hydraulic cylinders where the oil to the top of the piston is feed in at a connection on the end of the RAM, and then the ram has a hole down the middle to take the oil. This way, the visible hoses are very small. Can make for a lovely job, though you'd then have the complication of hiding the hose inside the 50mm s/s HT legs, which is perhaps some engineering too far. Just thought I'd mention the possibility!

 

[MapisM]

4. I doubt engine hatch stuff will do. It tends to be a bit mickey mouse sized, though I haven't surfed any catalogs. You will be wanting much heavier stuff, like say 20mm diameter for the ram and 50mm dia for the cylinder I think

Well, 20/50mm isn't much far from engine hatch rams, at least the serious ones.
Below is the one fitted on the Fountain, which has a pretty heavy hatch.
I'm not sure about its exact size and specs, but just by comparison with the ehaust tubes I'd say it's in that range. Don't know if it's double acting, either. But I know for sure (though never tried) that with a dead battery you can simply forget to lift the hatch manually.
So, I guess it's either double acting, in spite of no visible external hoses, or has some sort of safety lock when retracted.
And as I recall, some of these rams are available in polished s/s, and with impressive capacities, up to a thousand lbs. lift EACH!
Some of those guys over the pond take their e/r accessories rather seriously...

 

[jfm]

Below is the one fitted on the Fountain

Ooh, that's very nice. Single acting, and has a very neat integrated pump at the bottom. If it's st. steel it might be perfect for the HT - would be nice to avoid a lot of hydr piping installation. Most hydrs are make-able in several sizes so if you can get the name of the maker then they can probably supply what you need for the HT

Yup 1000lbs lift is easy. That's the great thing about hydraulics - the gearing is given just by altering the surface area. A 25mm ram, a bit like you pic, has surface area of .8 sq inches. Ordinary hydraulics are 3000psi so that's 2400lbs force. Heavier equipment can be 4000psi. You can double the force (and halve the ram speed, AOTBE) just by increasing the ram diameter x sq root of 2 (or triple it by increasing the ram dia by sq root of 3, and so on). Most of your engineering attention actually needs to be directed to making sure that the thing you attach the cylinder to is strong enough!

 

[AndieMac]

You couldn't pan out wide with a shot, to show the whole engine bay.....could you

Love to see the whole motor....

 

[kingfisher]

Well, the foldable hard top will deal with your cover/protection issues, but where are you going to put your radar dome and GPS mushroom?