JW's Upgrades for 2016 - Tender

[MapisM]

Yep, we had a great time indeed with all the forumites in CF this summer.
In hindsight, it's a pity that scubaman with his Phantom couldn't join us back then, because his videos would have been even more impressive with the whole forum fleet, compared to those recently posted, where there was just an old tub around...

 

[jfm]

I don't quite follow the wobble point, or at least I don't see why the relevant chock dimension is 180mm. If the keel is the main point of contact with the chock, and the sides of the V only hold the RIB upright, then surely that dimension can be as low as 20mm, and wobble wouldn't be much of an issue.

I mean wobble in the direction of the red arrows, about an axis that runs along the genoa track. I think it would be noticeable at the 180mm chock height as a flip flop side to side motion, if you use a single genoa track rather than two of them spaced apart. Of course people might not care about it, but I think it would feel a bit crummy. The pic is a Novurania 430 chock, Hurricane's exact new boat

 

[Hurricane]

Sorry for the later response - we did, in deed, get a lift this morning and the boys in the yard gave the boat a really good wash.
After pressure washing, we cleaned the props and stern gear using just soft brushes and aqua fuerte.
It seems that polishing them earlier this year really paid off.
Unfortunately, I didn't have my camera - but they literally gleamed.

Sorry - digressing

Thanks guys

Some interesting ideas.
Actually, I would prefer to have the Novurania the same way round as the Walker Bay.
It is easier to get to the engine for maintenance - flushing etc.

The rotation idea that MAPISM first mentioned sounds good at first but the stainless steel banisters around the hatch to the cockpit would stop the dinghy rotating.

Here are some more pics

Asm
Thanks for the post - I will have a good look at your suggestion.

The beauty of a sliding arrangement is that the operation is simple.
Simply load the dinghy onto the sliding chocks, stow the crane and slide the whole lot back.
The dinghy would then be as far back as it could possibly go.

 

[jfm]

This is tricky hurricane. Using the red marks on the tape to figure out where 39 inches (=1m) is, it seems there is almost exactly 1m of clear deck fore-aft length between crane foot print and aft edge of teak deck, when the crane is athwart ships. That means the keel of the dinghy (2m beam) will be along the aft edge of the teak, and to slide it 300mm aft the sliders and the chocks will have to project considerably abaft of the aft edge of the teak deck, which adds some complexity to the design. When the dinghy is slid back (I mean slid aftwards relative to JW) it is going to be cantilevered and the method of fastening the chocks to the deck will need to withstand upwards pull-out forces. Is that ok - can you get to the underside to install through bolts, for example? Alternatively, to avoid cantilevering, are you happy for there to be teak bases for the sliders, sitting atop both the teak deck and the white GRP aft of the deck, and going back as far as the stern light?

 

[Deleted User YDKXO]

Mike, I'm late to this thread so perhaps I'm misunderstanding the problem but have you considered raising the crane base so that the arm clears the new dinghy?

 

[Hurricane]

Mike, I'm late to this thread so perhaps I'm misunderstanding the problem but have you considered raising the crane base so that the arm clears the new dinghy?

Good point but the radar arch would be in the way.

 

[Hurricane]

This is tricky hurricane. Using the red marks on the tape to figure out where 39 inches (=1m) is, it seems there is almost exactly 1m of clear deck fore-aft length between crane foot print and aft edge of teak deck, when the crane is athwart ships. That means the keel of the dinghy (2m beam) will be along the aft edge of the teak, and to slide it 300mm aft the sliders and the chocks will have to project considerably abaft of the aft edge of the teak deck, which adds some complexity to the design. When the dinghy is slid back (I mean slid aftwards relative to JW) it is going to be cantilevered and the method of fastening the chocks to the deck will need to withstand upwards pull-out forces. Is that ok - can you get to the underside to install through bolts, for example? Alternatively, to avoid cantilevering, are you happy for there to be teak bases for the sliders, sitting atop both the teak deck and the white GRP aft of the deck, and going back as far as the stern light?

Yep - I think you have got a "hold of" and understood the problem.
On the face of it, the new dinghy will fit.
The first pic above - the long blue line (webbing) is approximately the centre line of the Walker Bay.
If I can arrange a sliding chock, the Novurania dinghy would end up on the same line (the Walker Bay currently has some space which the Novurania would take.
To recap, I'm not worried what this will look like (it will probably look quite silly) but it must be a strong engineering solution.

I hadn't thought of the cantilever forces that you mention and, of course, these are very important.
Though, I had thought of how to span the fibreglass moulding aft of the teak deck.
My thoughts were that a 50mm high piece of teak is screwed to the deck.
Then a second one is screwed to it to span over the fibreglass moulding.
Could even be fixed to the fibreglass to reduce the cantilever force.
Teak deck to the extreme edge of the fibreglass is 305mm.
See this pic

Getting to the underside of the flybridge might be very tricky - unless any fixings would line up with the Cantilupi light fittings.

I really do appreciate yours and others thoughts on this problem.
As you know, the Novurania is ordered and I'm really committed to finding a working solution to this problem.

 

[MapisM]

M, the more I think about sliding rails the less I like the idea, and in your boots I'd rather avoid it, if at all possible.
Your statement "I'm not worried what this will look like" popped another idea to my mind.
Could the Novu possibly fit without needing any sliding movement, If its chock would be made in such way to hold it listed to its port side?
I mean, by lowering as much as possible the port side of the Novu, couldn't you operate it normally, and avoid the hassle of any moving parts altogether?
You also said that you're aiming at a "strong engineering solution", and it doesn't get stronger than that....

The cons I can think of are as follows:
1) the tender would look weird, also because the most visible part (its stbd side) would be raised, and with the o/b in a funny position - but that's strictly aesthetic, and you knew in advance that the Novu wasn't going to be the ideal tender for JW from an aesthetic viewpoint anyway.
2) you should arrange the lifting cables in such way that the tender remains listed at all times, both when it's raised from its chocks and from the water. Of course, this would be a deal breaker as a normal way to lift the mother ship (or any big-ish boat), but it shouldn't be a problem with the rib.

And of course, it could be that the tender still interferes too much even if listed - in such case, again, just forget the idea....
But if this trick could work, 'fiuaskme I'd rather live with the poor aesthetic than fabricate any custom sliding solution.

 

[Deleted User YDKXO]

Good point but the radar arch would be in the way.

Not sure I understand that either! The lifting arm angle will be flatter but the overall height of the arm will be the same when lifting the dinghy. I was just thinking that when you buy that lump of iroko for the dinghy chocks you could make up a base plate to go under the crane base and with some longer bolts (presuming the crane is secured with bolts) to lift it say 50-100mm. Not sure whether that is sufficient to clear the new dinghy of course and not sure whether you can get at the bolts easily either.

Personally I don't like the idea of tracks. Apart from having to fix them well enough to resist the cantilevering effect of the dinghy when it is 'out' you will probably have problems getting inside the flybridge moulding to fix them. The other issue of course is that the tracks are going to have to be high enough to clear the moulding at the aft end of the flybridge and that makes the original problem worse by raising the height of the dinghy

All IMHO of course! Interesting problem though

 

[jfm]

Thanks for the extra pics and dims Mike. Thinking cap is on here, but have busy day with the day job. I'm still thinking a slider can work.
(We all need a meeting in SCM with a keg for this project )

I'll post soon some pics of my match 1 laser chocks, but I cant get p'bucket to work right now. They were blocks of teak flowing over aftwards onto the curvy GRP to remove cantilever loads, and provide a large area to attach them with 5200 (as well as bolts). I didn't like them in my application (just a lightweight Laser) and completely reworked them on Match 2 (pics of that above) but this might be exactly the right thing for your case

More later

 

[jfm]

Mike
Before getting into detailed slider design can I run this by you:

You make simple classic teak cocks that hold the dinghy in the "final stowed" position, ie the crane has to be perfectly athwartships else the "shoulder" of the crane hits the dinghy

To launch dinghy, first you open the valve for the port forward air chamber (there are 4 chambers) and let it go soft. Then you slew the crane from its parked position, lift the dinghy, and swing the dinghy out way from the crane by 300mm. You pause there, connect Cobra air pump and reinflate port forward chamber- takes 30 seconds. Then finish launch of fully inflated dinghy

Re-stowing is same - bring the dinghy up onto flybridge, to rest 300mm out from its final position, perhaps touching the aft chock to steady it. Then flick the air valve open for the forward air chamber, let that chamber go soft, finish putting the dinghy the last 300m to final position, slew the crane to the fully parked athwartship position, reinflate the dinghy with the Cobra to make it look tidy

Might sound some hassle but I doubt it is really much hassle to do this. Cobra pump is uber fast. The 4 air chambers are laid out as perfect quarters on the dinghy. You'd need a 230v supply on flybr (or maybe find a 24v fast inflator)

 

[Hurricane]

Mike
Before getting into detailed slider design can I run this by you:

You make simple classic teak cocks that hold the dinghy in the "final stowed" position, ie the crane has to be perfectly athwartships else the "shoulder" of the crane hits the dinghy

To launch dinghy, first you open the valve for the port forward air chamber (there are 4 chambers) and let it go soft. Then you slew the crane from its parked position, lift the dinghy, and swing the dinghy out way from the crane by 300mm. You pause there, connect Cobra air pump and reinflate port forward chamber- takes 30 seconds. Then finish launch of fully inflated dinghy

Re-stowing is same - bring the dinghy up onto flybridge, to rest 300mm out from its final position, perhaps touching the aft chock to steady it. Then flick the air valve open for the forward air chamber, let that chamber go soft, finish putting the dinghy the last 300m to final position, slew the crane to the fully parked athwartship position, reinflate the dinghy with the Cobra to make it look tidy

Might sound some hassle but I doubt it is really much hassle to do this. Cobra pump is uber fast. The 4 air chambers are laid out as perfect quarters on the dinghy. You'd need a 230v supply on flybr (or maybe find a 24v fast inflator)

Great - just like you to do some lateral thinking.
I like the idea and I think it would work.
But maybe use this as a backup idea if I can't get a slider to work.

The reason being that when the boat is rolling about, it is quite difficult to recover the current Walker Bay.
It would be even more difficult with the Novu.

Having said that, the intention is that we only need to store the Novu on the FB for long passages - most of the time it would be in the water or on a floating dock if we at our home berth.
At anchor, we would also leave it in the water overnight - we always like to prepare the boat for sea whenever we are at anchor - currently, that means putting the Walker Bay away but with the Novu, we would tow it if we needed to get away from an anchorage quickly.
So, maybe a deflation process would be acceptable for the fewer times that we stow the boat on the FB
I need to think about that - sounds a good solution.

Meanwhile - I've found these - which are interesting - not sure of price or availability.

http://www.pbclinear.com/Uni-Guide-Linear-Slide-System?tab=ProductOverview

Still looking though.

 

[MapisM]

Doh!
This made me laugh, because believe it or not, deflation was my first thought, but I didn't dare suggesting it because I feared that you were going to throw tomatoes at such non-kosher and a bit time wasting solution....
Btw, the total number of inflations/deflations can actually be half of what J envisaged, because there's no need to re-inflate it after putting it on its chocks - unless required for its cover, maybe?
Go for it M, you know it makes sense. No matter how solid and well built the rails can be, nothing can beat simplicity on anything boat-related! :encouragement:

 

[jfm]

Yes as regards reinflation - I only suggested it to make the dinghy look nice on the flybridge. I inflate mine using the Bravo* and it is unbelievably quick. No hassle at all. Depending on available flybridge locker space you could "permanently install" the inflator in a locker and just pull out an air hose and have a conveniently located on/off switch

*I think I've been saying "cobra" inflator. Sorry, I meant "Bravo" - this thing --> https://www.seascrew.com/browse.cfm?INFLATING-DEFLATING-PUMPS--FOOT--HAND---ELECTRIC&l=0000001017. It's brilliant. You can do a quarter chamber of this RIB in maybe 30 seconds

Mike, I get your point about difficulties when the mother ship is rolling. You would need to temporarily lower the dinghy onto something while inflating/deflating, so you might need a clever chock design that has a second little V cut out like this...

...but there again you could do the inflation after dropping the dinghy into the sea and you could do the deflation before even lifting the dinghy from the sea, then there would be no need to "pause" and do it on the fybridge as I was describing. Or you could fit a gyro or fins :encouragement:

 

[MapisM]

Or you could fit a gyro or fins

Hehe, see, Hurricane?
You start with the idea of fitting a longer anchor chain, and next thing you know, you are looking at a new boat, because it's less expensive than all the upgrades...

Jfm, very simple but clever idea the V cut out, I like it. Worth doing just to have the option of in/deflating both in the water and on the f/b! :encouragement:

 

[BartW]

I would also sugest the "deflating " solution, and check the exact position / limits with the Novu in situ, before designing a gliding mechanism.

Mike, are you sure that the FB overhang can handle the extra weight, and the CG is more to the back, ... ?
we have placed supporting poles under the overhang as you know, just to be sure

remembers me to this possible solution to fit a bigger tender on a P65; I found during my pre Blue Angel boat search ,
AndyMac will remember this one very well ;-)

 

[jfm]

Haha BartW, here is another beauty:

 

[Lloydroberts]

what an abomination.

 

[Deleted User YDKXO]

Haha BartW, here is another beauty:

Thats hideous. Why on earth did he do that when he's got a huge bathing platform to sit his dinghy on? He's probably knocked £100k off the value of his boat doing that as well.

 

[wakeup]

Yes as regards reinflation - I only suggested it to make the dinghy look nice on the flybridge. I inflate mine using the Bravo* and it is unbelievably quick. No hassle at all. Depending on available flybridge locker space you could "permanently install" the inflator in a locker and just pull out an air hose and have a conveniently located on/off switch

*I think I've been saying "cobra" inflator. Sorry, I meant "Bravo" - this thing --> https://www.seascrew.com/browse.cfm?INFLATING-DEFLATING-PUMPS--FOOT--HAND---ELECTRIC&l=0000001017. It's brilliant. You can do a quarter chamber of this RIB in maybe 30 seconds

Mike, I get your point about difficulties when the mother ship is rolling. You would need to temporarily lower the dinghy onto something while inflating/deflating, so you might need a clever chock design that has a second little V cut out like this...

...but there again you could do the inflation after dropping the dinghy into the sea and you could do the deflation before even lifting the dinghy from the sea, then there would be no need to "pause" and do it on the fybridge as I was describing. Or you could fit a gyro or fins :encouragement:

Would it be possible to set the tender chocks at a slight angle , say 15 to 30 degrees towards mothership bow there by avoiding sliding and deflating?