Tender garages

Innomare · 05-01-2006, 02:02 AM

Good thread,

K1W1, the positive experiences you have with stern garages, is that with an overhead crane in the stern garage or with a stern slipway (as shown on the Mirabella V picture)?

Bruno

PS, Anybody any experience with systems like this?
(Neptunus 55 Sport)

K1W1 · 05-02-2006, 02:14 AM

Hi,

My experience is with stern slipway type systems where the "trailer" goes out so there is no risk of pinching as there is nothing above the boat till it is drawn into the mothership.

An overhead beam out of the Stern has the same problem as the side ones. As the Tender goes up and down on the swell there will always be a risk of connecting with the beam unless it was metres above the boat and you would still have the cable snatch problem when there was any sort of sea condition.

Another thing that I forgot to mention about the Cranes and Tenders mounted on the Bridge Deck is the tendancy for people to ride the boats down. There was an accident on another yacht to the one I was on in the late 1990's that resulted in someone arriving from the shipyard where we were built to fit polished Stainless Steel plaques expressly forbidding the carriage of persons in the Tenders during launch and retrieval operations. I know this sort of action can be banned under standing orders but this is something that's very hard to enforce 100% of the time in a real life situation.

Sean · 05-02-2006, 09:29 AM

i think a stern launching arrangement is not always practical with all vessels. a lot of the time there is a requirement for an overhead launch or crane launch due to restrictions in space and configurations (aesthetic and practical). lets face it, if you owned a yacht you'd want to make as most of the space for you and your guests as you could. tenders would be a secondary thought for the crew to deal with, and a skilled crew will have no problems operating with overhead lifting arrangement for the tenders and toys.

personally i like the fold out hull type arrangement for launching toys, i'd fold my hath down and have a longer crane rather then pull it up and have a shorter crane. a beach bar or diving/fishing platform at a typical swim platform height is far more practical for me then sheer appearances

Codger · 05-02-2006, 11:56 PM

The port side tender garage on Octopus looks to be at least 2 metres above the water line. That could be a fair bit of mass swinging about on cables.

K1W1
Isn't there a feed guide/pressure plate on the winch to prevent it jumping?

K1W1 · 05-03-2006, 06:44 AM

Hi,

The use of bottom hinge doors is good in theory for the reasons stated but not so good in practice as you would need to have much sturdier beam cranes which would require more interior space to carry the runners etc and you would be much more suseptable to getting hit by the beams when the boat was rolling simply because you would have to lift and push your boat out the extra distance to clear the door which on an average deck height would be 2 m.

You would have the weight of the Tender ( one of our present ones is 5000kg) plus the beams an extra 2m out from the shipside. The "dip" of the beam as the boat rolls would also be increased markedly as would the loading on the door as waves came up under it.

KCook · 05-03-2006, 09:57 AM

Possibly dumb question (my personal specialty) - but are those big bottom hinge doors locked down in position or allowed to float?

Kelly

Yacht News · 05-03-2006, 12:27 PM

i think that hey are locked down...although i could be subject to correction

K1W1 · 05-03-2006, 03:56 PM

Hi,

The two stern launching systems I have been involved with both hold the doors down with hydraulics when launching and or retrieving.

The hydraulics have to be man enough to submerge the door in the first place as well.

After the Tender is launched the Doors are returned to the horizontal position or it can be closed if the main boat is going to move and the Tender is going to be elsewhere or whatever the operational requirements require.

KCook · 05-03-2006, 05:10 PM

Humm, fun to contemplate. At this point I'm wondering if the type with the platform separate from the door, as seen in the photo in Bruno's post, is more practical than a bottom hinged door .....

Kelly

Yacht News · 05-03-2006, 10:22 PM

I often wonder how does Octopus get her main tender out " Man o WAR" out of the marina garage. When the stern door is opened the boat can only come so far. When she wants to leave the mother ship what happnes? I know that there is a set of steps in the middle of the bathing platform. I wonder if this area is forced down into the water by hydraulics like seen in Bruno's post or if they are retracted somewhere to allow the tender to pass in and out of the mother ship?

brandonw · 05-03-2006, 10:28 PM

Quote:

Originally Posted by Innomare

PS, Anybody any experience with systems like this?
(Neptunus 55 Sport)

Do you know what size tender goes in that garage?

WannabeeYhtsman · 05-05-2006, 12:05 PM

I too have been very curious as to how the main tender garage works on Octopus.

I assume it works like a dry dock that can be filled to sea level when exit/entering is required and pumped dry with vessels secured during voyage. What about the center transom platform, does it lower into the water?

Cheers all

Ben · 05-05-2006, 07:14 PM

Quote:

Originally Posted by WannabeeYhtsman

What about the center transom platform, does it lower into the water?

Yep.

.

Innomare · 05-09-2006, 06:21 AM

Quote:

Originally Posted by K1W1

Hi,

The two stern launching systems I have been involved with both hold the doors down with hydraulics when launching and or retrieving.

The hydraulics have to be man enough to submerge the door in the first place as well.

After the Tender is launched the Doors are returned to the horizontal position or it can be closed if the main boat is going to move and the Tender is going to be elsewhere or whatever the operational requirements require.

K1W1, about the trailers used on the stern platform, do you know which was the supplier? Were the trailers rolling on the stern door or cantilevered above it? Are the pictures in attachment a correct representation?

With regards to the Neptunus-photo in my previous post:
- I don't know the size of the tender.
- It looks ideal, because you have the luxury of the platform lift also when the tender door is closed. That is great for older people or divers. Climbing up a standard swimladder can be hard, especially if there's some rolling going on. With the swimplatform lowered, you can just swim over it and stand up.
But: If the lift mechanism ever breaks down, you're left without a tender. I wonder if the MCA would accept that if the tender also has to be the rescue boat. Maybe they accept it if you can lower the platform with a manual pump? Anyone any experience?

Bruno

K1W1 · 05-09-2006, 08:41 AM

Hi,

Bruno; On the boat in your picture the trailer was powered by hydraulic motors in the front that drove two sprockets and a large pitch stainless steel chain was laid in the bottom of the tracks. The trailer travelled all the way out in tracks to the aft end of the platform where it was retained by two small stainless steel clips welded onto the door frame. The front under section of the trailer pivoted so when the trailer was on the door and it went down the drive section stayed down on the deck in the drive position. The rams of the door did all the up and down action of the boat, trailer and door. The sytem in use at present on there has had major modifications and now works a lot better.

The one I am dealing with now doesn't touch the door at all, the door goes down and then the trailers go down but stay clear of the door at all times.