Reply
 
Thread Tools Search this Thread
 
Old 17 June 2006, 14:16   #1
Member
 
Country: USA
Town: Fairfield
Boat name: Sunrider
Make: Zodiac
Length: 7.3
Engine: MerCruiser (bio)diesel 180hp I/O
Join Date: Jun 2002
Posts: 298
boarding ladder at the bow - and dive platform

I'm rebuilding a 30' ex-military RIB and am wondering if it's practical to build a boarding ladder into the bow. I've attached an image of a boat in Australia that has one to give an idea of the concept.

I am also interested in any pictures you might have of aluminum dive platforms that extend from the transom - especially any that fold down from a radar arch or similar.

I would appreciate receiving pictures, advice, suggestions, references and comments on either idea. I'm ordering new tubes this week so any quick suggestions on how to integate the bow ladder would be especially appreciated.

thanks.
Attached Thumbnails
Click image for larger version

Name:	bow ramp (Small).jpg
Views:	341
Size:	42.5 KB
ID:	20232  
__________________

__________________
sunrider is offline   Reply With Quote
Old 17 June 2006, 18:24   #2
Member
 
Country: UK - England
Town: Portsmouth
Boat name: Sting
Make: Tornado 6.8
Length: 6m +
Engine: Yam 200 HPDI
Join Date: Oct 2002
Posts: 637
Send a message via MSN to Andy
Scorpion did one like this also:

http://www.scorpionribs.com/superyacht.html

But it's a boarding ladder not a dive ladder. The bow is the highest and narrowest point. It makes little sense to put a dive ladder at that point. The ones I have seen hang off the A Frame and have that to mount against. Far better choice to take the load.

Take a look at these:

http://www.boat-finder.com/images/bo...1_Demo2003.JPG
http://www.boat-finder.com/images/bo...SeatLadder.jpg
http://www.boat-finder.com/images/bo...oatDistant.JPG

It's a propper dive ladder you could climb with fins. Room to get in the boat kitted. Lowest point of the boat so less of a climb and less movement caused by waves. Much easier to place next to the diver, visability is better, than off the front of the bow. I have never seen this used, not sure how strong it is.

Then if you have the space this is amazing, a ladder and lift! I have used this and its excellent:

http://www.kierman.co.uk/data/galler...N0065_PNG.html
http://www.kierman.co.uk/data/galler...N0060_PNG.html
http://www.kierman.co.uk/data/galler...N0055_PNG.html

Then again I am not a boat builder so what do I know!
__________________

__________________
Andy

www.badviz.com
Andy is offline   Reply With Quote
Old 20 June 2006, 01:13   #3
Member
 
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
Hope you're talking about boarding from shore through (or over) the bow.

Wouldn't want to have to do that in dive gear, with the bow pitching up and down in 5 foot swells...

jky
__________________
jyasaki is offline   Reply With Quote
Old 20 June 2006, 19:04   #4
Member
 
Country: USA
Town: Fairfield
Boat name: Sunrider
Make: Zodiac
Length: 7.3
Engine: MerCruiser (bio)diesel 180hp I/O
Join Date: Jun 2002
Posts: 298
Yes, the bow ladder would be used only for boarding when beached, not at sea. those links are very helpful and I've emailed Scorpion to see if they will provide more pictures and info on their bow ladder.

I've looked at the pole type boarding ladders for divers previously and hope to have at least one on board that can be moved to several side positions rather than a permanent mount - but would like the primary boarding for divers to be available through the transom. As I'm imagining the platform it would be dual purpose - when moving it would stand vertically and serve as a backrest or perhaps bench seat, and when at rest could/would be folded out over the transom as a platform. So I'm especially interested in seeing examples that show how the aluminum is joined, and at what level(s) it might rest in relation to the water. The link to the powered transom lift was very surprising - gets me wondering if I could power such a device from the hydraulic system that controls the jet buckets(?).

thanks again for the info and links...more are welcome...
__________________
sunrider is offline   Reply With Quote
Old 21 June 2006, 13:36   #5
Member
 
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
Problem with over-the-side ladders on inflatables is that when you step on them, they have a habit of swinging up under the boat. You need to fix them so they stay more or less vertical in the water (which can take some work.)

Which, of course, is why I went with a swing down ladder at the back of the boat (hinged off the back of the motor bracket, which makes a pretty good swim platform, as well.) I'll see if I can get a couple of pics sometime.

jky
__________________
jyasaki is offline   Reply With Quote
Old 21 June 2006, 17:59   #6
Member
 
Country: USA
Town: Fairfield
Boat name: Sunrider
Make: Zodiac
Length: 7.3
Engine: MerCruiser (bio)diesel 180hp I/O
Join Date: Jun 2002
Posts: 298
Sounds like ggod advice...I look forward to the pictures when you find time...thanks.
__________________
sunrider is offline   Reply With Quote
Old 21 June 2006, 19:06   #7
Member
 
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
You're anticipating too much. Just a 3 or 4 rung (can't remember now) christmas tree ladder out of square aluminum tube (though the top section has a solid bar hammered into it for strength.) Pinned in using a drawbar pin (that holds a drawbar to a trailer hitch) on a fabbed up bracket that bolts to the swim step. Swings up for travel, and down to recover divers.

jky
__________________
jyasaki is offline   Reply With Quote
Old 21 June 2006, 19:35   #8
Member
 
Country: UK - England
Town: Portsmouth
Boat name: Sting
Make: Tornado 6.8
Length: 6m +
Engine: Yam 200 HPDI
Join Date: Oct 2002
Posts: 637
Send a message via MSN to Andy
Quote:
Originally Posted by sunrider
The link to the powered transom lift was very surprising - gets me wondering if I could power such a device from the hydraulic system that controls the jet buckets(?).

Its powered by 2 electric winch motors and fabric straps wind in to pull the platform up ... really excellent!
__________________

__________________
Andy

www.badviz.com
Andy is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 03:44.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.