Dinghy mounting on Swim platform - Chocks...?

[RogerRat]

I'm going to be mounting my next dinghy on chocks on the swim deck if I can find some...

I would like them to be quickly detachable too, but only when required.

Can anyone offer suggestions on where to source these mountings as often seen on Princess' and Squadrons'. Also best method of mounting.

The dinghy itself will most probably be handled/lifted by the passerelle and held down with ratchet straps.

 

[rafiki_]

I have the Hurley davits, which do the same thing, plus the benefit of a launch and recovery system.

 

[RogerRat]

I have the Hurley davits, which do the same thing, plus the benefit of a launch and recovery system.

Nope, not quite the same thing, but I wouldn't rule them out. They're made of nylon but don't offer much support to the dinghy's keel.
Thanks tho.

 

[stelican]

I'm going to be mounting my next dinghy on chocks on the swim deck if I can find some...

I would like them to be quickly detachable too, but only when required.

Can anyone offer suggestions on where to source these mountings as often seen on Princess' and Squadrons'. Also best method of mounting.

The dinghy itself will most probably be handled/lifted by the passerelle and held down with ratchet straps.

What type/size of boat do you have

 

[sarabande]

what about the kind of floor track that is used for aircraft seats ?

http://www.ancra.com/aircraft/track.html



(Glad to see you back in boaty action )

 

[rafiki_]

Nope, not quite the same thing, but I wouldn't rule them out. They're made of nylon but don't offer much support to the dinghy's keel.
Thanks tho.

My dinghy is a rib, and the floor slots nicely into the chocks.

 

[RogerRat]

What type/size of boat do you have

It'll be a 275 Rib with a Yam 8Hp 2 stroke. So nothing special. Total weight about 75 KGs' all up.

 

[RogerRat]

what about the kind of floor track that is used for aircraft seats ?
(Glad to see you back in boaty action )

Some of those look pretty meaty but I would like to avoid digging up my brand new teak that's currently being replaced. I would like to do minimal damage to the teak and hopefully find a notched keyhole locator system.

Not been a way, still on the same boat just not been on the Forum much due to lack of time really.. Thanks though.

 

[MyMarine]

Probably best to have 2 blocks of wood made to the profile of the hull and then sat into the platform on stainless pins. Make the template from thick cardboard.

 

[RogerRat]

Probably best to have 2 blocks of wood made to the profile of the hull and then sat into the platform on stainless pins. Make the template from thick cardboard.

Thanks, the profiling is fairly straight forward and that's what I had in mind too.

It's the 'Stainless pins' into what? is what I am trying to source...

 

[sarabande]

oversized Dzuss fasteners ?

http://www.southco.com/en-gb/product/hierarchy.html?hid=7345


Some other types of hold-downs on the site as well.

 

[lanerboy]

I asked a similar question a while back and JFM added this reply

Shawn, a passerelle will as Terry said be £10k kind of price. On my Phantom 42 we had a Valiant 2.8m RIB and 5hp outboard (the lovely Merc/Mariner/Tohatsu 2 stroke, of which I hope you can find one 2nd hand) and we just lifted/dragged the thing from water straight onto the chocks with the engine always attached not removed. Easy peasy. The chocks had a sliding "ramp" part to their profile, at the aft end, which was very helpful because it allowed us to drag the dinghy up the ramp and into the V of the chocks, without bashing the mothership's gelcoat. See pics. This is what I would do on a 40 footer

he then added this

Blocks of teak in 50mm x 180 section, from kj howells. About 70 quid for the pair nowadays. Yes, cut to hull shape of tender. Removeable (for when swimming), and attached to deck using a 50mm x 4mm length of s/s strip screwed to bottom of chock, and with an M8 or 10 thumbscrew going into threaded "upside down top hats" set flush into the deck

 

[jfm]

Roger you need to get upside down top hats custom made. They're not a catalogue item. The flange should be 6mm thk to match the teak, and the dia to match your holesaw eg 51mm The hole in the middle can be plain (for drop in pins) or threaded M10 say, or can be keyhole and then you have a mushroom on the bottom of the chock to locate. But all has to be custom made

I have some spares but I think they're on the boat. If I find them at the weekend I'll post again

 

[MapisM]

Can anyone offer suggestions on where to source these mountings...

I've seen some adjustable steel chocks (covered with rubber on the upper surface which supports the dinghy) on BartW boat.
They might be catalogue items, but I'm not sure. You might pm him, if he doesn't see this thread.

Otoh, the most common solution is definitely with wooden chocks cut to measure, which is also what I had made for my boat.
Btw, this allows a small but handy customization, i.e. making a small step in the stern chock.
This is useful for two reasons: on one hand, it gives a fixed reference for positioning the dinghy in the right place, and otoh you always have the chock supporting exactly the dinghy transom, rather than potentially leave it (and the o/b, obviously) overhanging.
'Dunno if the explanation is clear enough, if not tomorrow I can take a pic and post it...

 

[RogerRat]

Roger you need to get upside down top hats custom made. They're not a catalogue item. The flange should be 6mm thk to match the teak, and the dia to match your holesaw eg 51mm The hole in the middle can be plain (for drop in pins) or threaded M10 say, or can be keyhole and then you have a mushroom on the bottom of the chock to locate. But all has to be custom made

I have some spares but I think they're on the boat. If I find them at the weekend I'll post again

I think I understand what you mean but I might just have to look at few teak blocks and how they're mounted. The top hat is usually used for inverting, yes?

You wouldn't have a piccy on file anywhere close?

 

[jfm]

I think I understand what you mean but I might just have to look at few teak blocks and how they're mounted. The top hat is usually used for inverting, yes?

You wouldn't have a piccy on file anywhere close?

I'm getting confused (!) mapism wrote about the chocks themselves and suggested cutting from teak blocks (which i agree with, btw). My post however was about the stainless steel mounting stuff, not the actual chocks. i thought that is what you were asking about - you asked about "mountings" for chocks, not chocks per se. But did I misunderstand?

i'll try to post some pics later but what do you mean by "inverting"

 

[RogerRat]

My post however was about the stainless steel mounting stuff, not the actual chocks. I thought that is what you were asking about - you asked about "mountings" for chocks, not chocks per se. But did I misunderstand?

Thanks for clearing this minor confusion. YES - you understood my request. I was asking about the mounting of whichever chock I adopt. I like the teak and the idea of a keyway to allow quick removal.

On reading your reply again, the 'top hat' will allow for an upside down M10 bolt head to locate in a keyway mounted into the swim platform, I believe. As I had seen so many boats with this arrangement I had wrongly assumed this was an 'off the shelf' solution.

If you can find any pics, it would certainly help, especially the parts attached to the swim deck.

I also like the idea of incorporating the slide ramp into the chocks as on the P42 (posted picture in a previous reply of yours) to allow for easy launch and recovery. I am now thinking that I could have these fabricated in stainless, say 50mm wide 6mm thick and formed to a 'V' to match the hull profile. Of course they would be handed so I would need to ensure the dinghy is always the same way round. If I then extended the ramp aft this would create a launch and recovery ramp. I could then attach rubber layer to the metal chocks to protect the GRP of the dinghy. Tie downs would then be straight forward as long as the chocks were secure.

I know you have done this a few times so I would appreciate your thoughts?

 

[MapisM]

I was asking about the mounting of whichever chock I adopt. I like the teak and the idea of a keyway to allow quick removal.

I'm puzzled by the debate on mounting hardware, maybe I'm missing something.
Do you want to have the chocks securely bolted to the platform, for some reason?
I'm asking because as long as you keep the dinghy on them, OR you throw them in a locker when not used, there's no reason to bolt them to the platform at all.
My chocks have two steel pins each, matching two holes in the platform, just to keep them from moving sideways.
I put them in place when I need them, and pull them up when I don't. Can't think of anything more convenient.
I'll take a pic tomorrow, as they say it can be worth a thousands words...

 

[RogerRat]

I'm asking because as long as you keep the dinghy on them, OR you throw them in a locker when not used, there's no reason to bolt them to the platform at all.
My chocks have two steel pins each, matching two holes in the platform, just to keep them from moving sideways.
I put them in place when I need them, and pull them up when I don't.

Thanks for following the plot, that's what I have in mind too but I'm not keen to drill holes through the platform to push steel pins through. The idea of the inverted studded M10 bolts is to maintain the integrity of the platform but also allow easy removal as with your drop in pin locators.
So we are on the same page really.

 

[jfm]

I'm puzzled by the debate on mounting hardware, maybe I'm missing something.
Do you want to have the chocks securely bolted to the platform, for some reason?
I'm asking because as long as you keep the dinghy on them, OR you throw them in a locker when not used, there's no reason to bolt them to the platform at all.
My chocks have two steel pins each, matching two holes in the platform, just to keep them from moving sideways.
I put them in place when I need them, and pull them up when I don't. Can't think of anything more convenient.
I'll take a pic tomorrow, as they say it can be worth a thousands words...

If Roger wants to use the slide ramp idea with ramps that project over the stern, like phantom 42 above, as opposed to lifting the dinghy on with the passerelle, then the simple pins wont work. Otherwise I 100% agree with you. But I do not know the full spec for this project!

BTW, and not relevant to Roger's question, the simple pins don't work with an up-down platform because the chocks float away. How do I know that ???!