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landlocked sailor
11-03-2011, 05:24 PM
I want to carry & launch my Oughtred AUK from the cabin top of my BlueJacket 28, using a mast/boom mechanism. Does anybody have any rule of thumb dimensions for such a rig? I envision a short folding mast in a tabernacle, carrying the dinghy upright. I have the photos of such a rig on Heart of Gold but little detail. Rick

Jamie Orr
11-03-2011, 05:58 PM
A friend launched and retrieved his 9 or 10 foot (much heavier than the Auk either way) fibreglass tender with the halyard alone, hauling the dinghy up by the nose. He was able to do this without help, although an extra pair of hands was welcome. You may want to try this before spending time on an extra spar that will take up additional deck space?

Lovely design though - I saw one on another page being built as tender to a "modern knockabout", is that you?

Cheers,

Jamie

landlocked sailor
11-03-2011, 06:03 PM
Jamie, my boat is a power cruiser www.bluejacketboats.com so there is no spar as yet. If Mike Field posted the picture then yes, it's mine. Rick

wizbang 13
11-03-2011, 06:21 PM
I carry 2 hard dingys , and have, for a LONG time.
To board, I bend over the rail, grab it in the middle, and lift. One yank, she is up and balanced on the lifeline. Then I get my knee under the dink and pivot my self 90 degrees and set her down.
Launching is pretty much the opposite.
Problems come with dingy rub rails, fenders, haliards, spectaters tellin you what yer doin wrong, ect.
My wifes' El Toro is about 80 pounds, my 11'er is slightly over 100. I'm 57 and weigh 155 lbs.http://farm5.static.flickr.com/4007/4647827136_27c0386d7b_z_d.jpg
For carrying, I just frap them down, no chocks. i adjust the frapping as the weather increases.

yesiam
11-03-2011, 08:27 PM
You just have to love wiz's rugged straight forward rough and tumble common sensical and KISS approach to most things nautical -- Gene

Breakaway
11-03-2011, 10:39 PM
Check out this thread by fellow forumite, Tom Larkin.
http://forum.woodenboat.com/showthread.php?124597-9-foot-rigid-dinghy-on-a-25-foot-boat&highlight=

Kevin

snow(Alan H)
11-04-2011, 02:05 AM
Short mast version for your reference

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/Mastdinghydavitexample.jpg

landlocked sailor
11-04-2011, 12:34 PM
Thanks for your replies everyone, I really appreciate it. A dinghy is pretty much essential while cruising on the Chesapeake. We are currently "marooned" on board in Annapolis harbor until the water taxi starts service at 1600. We had hoped to make the st. Michaels oyster festival tomorrow but have no way to get to shore.
Kevin, my boat has a stern cockpit so that flip aft launching really isn't an option. I am pretty much limited to carrying on the cabin top.
AlanH, those kind of pictures are exactly what I need. Now I need some details, dimensions, rigging, etc.

Rick

landlocked sailor
11-04-2011, 12:41 PM
Wiz, I have to haul that sucker up on the cabin top, about 6.5' from the water so I will need some mechanical advantage. I like your minimalist approach though. Pete Culler said " to be successful at sea we must keep things simple". Rick

Ian McColgin
11-04-2011, 01:20 PM
It'll be nice if you can locate the mast and boom such that you don't need to boom up or boom down when you swing from amidships to over the side. The boat looks narrow enough for that.

For this boat, I'd plant the mast up the aft end of the cabin with all the working action in front. From the cockpit deck to just above the height of the dink's transom when stowed would be essentially a tabernacle with the boom just below the joint. That way, the boom can lay just above the dink centerline and the mast above that. Some sort of brace that essentially plugs into a hole in the dink's breasthook would be nice to hold things still when folded down.

With this arrangement it's possible that a stay set up with a pelican hook to each corner of the transom is all you'll need, but that will take a little experimentation.

The steeper the boom angle, the less strain on the boom halyard but you're limited by what looks good. You might not actually need control of that halyard for the simple job of hoisting the dink, and a simple cable might do the job. For the hoist or load halyard you might find a simple wind-up trailor winch the easiest thing to use.

A key problem to solve is how to attach the dink to the crane hook. The lightest simplest might be lifting rings inside lagged into the keel or bolted through it. The closer they are the less stress but you want them far enough fore and aft of the center of mass that the thing is stabile. It could be two lines connected to a strong ring or shackle. Coming up to the lifting ring from the gunnel on either side of the center of mass would be another pair of lines such that all four are tight at the same time. If you can get all this to work out to a ring that's within a foot or two of the gunnel, then you'll have more convenient room to work with during the pick.

I'd use nice strong snap shackles at the ends of those lines to attach to the dink. You might as well have the lines permanently attached to the hoist so that they are always at hand when needed and left out of your way when rowing or motoring away from the mother ship.

G'luck

JoshuaIII
11-04-2011, 01:33 PM
It work really well with the halyard alone, which I have done for years. I sometime use the whisker pole so the halyard is pushed further out which does not let the dingy bang against the hull when I am doing it alone.

snow(Alan H)
11-04-2011, 01:38 PM
A more modern version - on some boats the 'pole' is in sections & can be removed for storage below

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/190457842_full.jpg;

landlocked sailor
11-05-2011, 08:07 AM
Ian, I read your post before bed last night and was befuddled. Got up this AM and the mate and I drew a sketch. We would not be able to have the hinge that high; there is not enough head room in the boat barn. But there is nothing stopping me from stepping a solid mast on the cockpit sole and having a mast gate on the edge of the cabin top. This might even obviate the need for stays. The mast would easily stow in the cabin or cabin top while trailering. Having the boom face forward looks a little funny to my eye but I think I could get used to it. Another theoretical advantage is a place to fly a small riding sail. I admit though that I am still trying to picture your description of lines attached to the dink. A bit more sketching is in order I think
Alan, I am having trouble seeing the rig on St. Clair. Is it folded in that picture?

Rick

snow(Alan H)
11-05-2011, 12:15 PM
Alan, I am having trouble seeing the rig on St. Clair. Is it folded in that picture?

Rick

Have a look here

http://www.trademe.co.nz/Browse/Listing.aspx?id=414829628

landlocked sailor
11-06-2011, 07:57 PM
I want to put this:
http://db.tt/MxCqTWJS

On top of this:
http://db.tt/TJvLIfcB

Rick

landlocked sailor
11-06-2011, 08:20 PM
Sorry. I just got a tutorial on posting photos from my daughter. Rick

Yeadon
11-06-2011, 08:34 PM
Your boat might look cool with a small yet functional boom aft of the cabin top. Worth sketching it a few times. Might be just the salty answer you seek.

JoshuaIII
11-06-2011, 08:41 PM
If you cut the roof, put some ballast in the bottom, changing a bit the shape of the boat, make a new mast, steping it with the new chainplate on the boat, removal of the engine for the ballast and some sails... You can use the halyard to raise you dingy!

Simple & efficient! ;)

Lew Barrett
11-06-2011, 08:52 PM
How elegant does it need to be?

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/Mastdinghydavitexample.jpg
Gwendolin's solution (that's Gwendolin, Alan) is one of two trad approaches.

Mike's sleeved davit is the other. Many boats (as does mine) have two of these, but with a small, light boat you could get by with one. I had a spare, but gave it away years ago.
The details of mounting and rigging it will keep a grown man entertained for weeks!

http://i240.photobucket.com/albums/ff76/LewBarrett/Dawnlines-1-1.jpg


With either, you are going to need a set of chocks form fitted to the bottom of the dinghy. That's a fair bunch of fabrication and penetration to put the small boat on the roof.

Swim step and snap davits? The snap davits were for an Avon. The wooden chocks were for an 8 foot Monk pram.
We usually went with the Avon.

http://i240.photobucket.com/albums/ff76/LewBarrett/vptrans.jpg

Woxbox
11-06-2011, 08:57 PM
That's a very nice but a deliberately light boat. Does the designer have any comments on carrying such a dinghy on top? I'd want to know how the stability and roll would change.

Lew Barrett
11-06-2011, 09:06 PM
I'd be surprised if such a light dinghy would make a difference there, that is strictly in respect to stability, but the work involved in making and mounting davits or a mast and yard with proper lifting tackle shouldn't be underestimated. Also, there is a lot of stress on various arms and pieces when you get the boat over the side, so that stuff needs to be robust. And there are all those penetrations.....

A simple solution is definitely worth exploring first. Is towing out of the question?

I thought Joshua had an amusing reply (:D):


If you cut the roof, put some ballast in the bottom, changing a bit the shape of the boat, make a new mast, steping it with the new chainplate on the boat, removal of the engine for the ballast and some sails... You can use the halyard to raise you dingy!

Simple & efficient! ;)

snow(Alan H)
11-07-2011, 03:45 AM
This is what I was thinking - 'simple' single davit.

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/Woodentopsidesidea.png;

Hwyl
11-07-2011, 04:37 AM
I would build a removable ramp that crosses the transom and the aft end of the cabin top. You could either mount the trailer winch on the ramp extension or the cabin roof.

So this would be prototype1:

Take 2 2X4's screw in chocks with carpet protection where they lay on the transom and roof. Lay them out like railroad tracks, with 3/8 line being the railroad ties.

Put the railroad in place, grab the dinghy and pull it's bow over the transom and onto the bottom of the railroad. secure it to the winch line.

Wind like crazy.

Drag the dinghy onto chocks on the cabin roof,

Put railroad away.

Enjoy beer.


I want to put this:
http://db.tt/MxCqTWJS

On top of this:
http://db.tt/TJvLIfcB

Rick

Breakaway
11-07-2011, 08:55 AM
I would think for a davit, you would need to run the post/mast for it right through the cabin cabin roof and through the cabin sole into keel/bottom somwhere. Maybe against the cabin bulkhead, alongside the companionway framing? Its a light boat, but out on a lever arm so how much does it "really" weigh when being hoisted. Miy instinct is that is seems like a lot of stress for just a surface mount with a backing plate through the roof, though I am no guru :)



What does Tom Lathrop say about these suggestions?

Kevin

Lew Barrett
11-07-2011, 01:02 PM
This is what I was thinking - 'simple' single davit.

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/Woodentopsidesidea.png;

That is Zella C, 40 foot LU Dreamboat, and that davit is almost certainly a later addition. Single davit is the only thing here that makes any sense if mechanical advantage is desired, (if not, something like Hwyl's solution is worth a look) but another thing that needs to be decided is where the guy who is launching and retrieving is going to perch himself. You need two hands in the best of scenarios with these rigs. This set up may well require three! The average human only comes with 1.5 unless they are ambidextrous!

The "dinghy problem" is a drag with a 40 or 50 foot boat, never mind a smaller one. Any Chris Craft has similar problems; carrying dinghys was never really part of the plan for most of those.

Towing is not fun in a lousy sea state (on my boat, often troublesome in a following sea) but it is simple. How often do you get lousy seas?

landlocked sailor
11-07-2011, 07:28 PM
We actually tried towing last week and it was a definite FAIL! At anything faster than displacement speeds she sticks her nose up so high that she fills from the transom. We routinely cruise at 14 knots so that's a no-go.
The single davit would probably work well; bolt the base to the deck and support the pole at the cabin top with a strap. We could handle the dinghy from the cockpit and through the window from the cabin. Where does one find such a davit?
Lew & Hyl, the outboard pretty much prevents any stern options. I have a small swim/boarding platform to port, but I need to be able to trim the motor up. http://db.tt/btb8I6f6
Josh, as a lifelong sailor, this is really my first "stink potter". Sailing is a lovely & poetic thing to to; but it ain't no way to get anywhere.
Rick



http://db.tt/btb8I6f6

Lew Barrett
11-07-2011, 09:12 PM
You'll either have to fabricate it or have it made; I don't think you'll find an off the shelf solution. Pipefitter would be your man if you were in Florida, but I am sure there is somebody in PA with the ability if you don't want to tackle it yourself. Mine are some kind of mild steel and are in two pieces. The "sleeve" which on mine is threaded (male) at the bottom is fitted into a female base that is bolted to the deck. That base piece is relieved to allow water out in the event ("event" should be in quotes!) water gets into the tube. The top piece is bent to form and fits into the "base" tube. It telescopes up and down in the tube. For running, it is in the down position. To deploy, it is lifted and a pin is inserted into a hole in the bottom tube. This keeps the top piece extended so the blocks can do their work and lift the small boat off it's chocks. I will try and take some detailed photos for you in the next few days, pictures being worth a thousand words and all that. My set up is quite typical for this sort of rig.

In Mike's (erster's) photo the idea is a bit different than what I commonly see up here, but the overall idea is the same.
This will not be a cheap project because just the blocks will run to several hundred dollars unless you make them or find a suitable used set. I'm sorry you aren't here a few years ago: I had one laying around and finally either gave it away or tossed it (OMG!) because I couldn't find anybody who needed it!


By the way, I routinely tow at eleven or twelve knots. The trick there is a VERY LONG painter. You see guys towing at high speed all the time up here. The bow eye in the dinghy needs to be down low, and the painter needs to be very long if you intend to tow over hull speed. Some boats do tow better than others, but it should not be that hard to figure out how to rig to do it. Towing with an outboard would seem to complicate things, I admit.

Durnik
11-07-2011, 10:55 PM
If you cut the roof, put some ballast in the bottom, changing a bit the shape of the boat, make a new mast, steping it with the new chainplate on the boat, removal of the engine for the ballast and some sails... You can use the halyard to raise you dingy!

Simple & efficient! ;)

From one blow boater to another.. Yea, that's about right..

sweet dink, tho.. just needs a mast & sail.. ;-)

enjoy
bobby

landlocked sailor
11-08-2011, 08:18 AM
Thanks Lew, I appreciate your detailed and thoughtful comments. When you say VERY LONG, how long is that?

Durnik, how about this?http://db.tt/xV6O1aBm

Rick

Durnik
11-08-2011, 12:02 PM
Thanks Lew, I appreciate your detailed and thoughtful comments. When you say VERY LONG, how long is that?

Durnik, how about this?http://db.tt/xV6O1aBm

Rick

Flutter, flutter.. sails & heart..

Tho I see what you mean by 'landlocked sailor' ;-)

enjoy
bobby

Lew Barrett
11-08-2011, 06:39 PM
How far back you set the dinghy when towing is a matter of boat length and speed; it can be varied according to how fast you are traveling. How it usually works for a displacement boat is that you let the painter out so that the towed boat rides in the "second" stern wave, in my case that is just slightly bow down with the Avon. If towing the wooden boat, I will let the bow ride a bit higher. It is very adjustable according to painter length, the desired attitude o the towed boat and boat speed. When you get the distance right, the boat will essentially be surfing in the stern wake. For my fifty foot boat at hull speed, that's about 40-48 feet (where/when the bow and stern waves join together). I say 40-48 rather than 50 because I want to allow the small boat to surf that wake, so with a ten foot dinghy, the painter will be let out about 42 feet, plus or minus. When the pressure on the line is at it's least, you are there. As you move beyond hull speed, the painter needs to be let out more. My boat never gets up on plane, even at 14 knots, but the practice of setting the dinghy to ride that wave "just so" dictates the distance the painter is let out. For a thirty foot boat that is planing, how far back is entirely a question related to how fast you will go. A fifty foot painter (at a guess) might be right for that approach. Another towing strategy is to make a painter long enough to get entirely past the stern wake so it tows in the quiet water "out there." That could be several boat lengths. Typically, you experiment with a long line until you found the sweet spot at your standard cruising speed and then let it in or out a bit if you change speeds. When you get close to a dock or anchorage, you haul the thing in close so it doesn't get in the way and also so that you don't run over the painter, which always makes a mess! Once you understand that you are trying to tow efficiently (least pressure on the line) and in an attitude that keeps the dinghy dry, you have it knocked.

I didn't get to take any pictures today, but will tomorrow. What Mike says about Pipefitter's work is on point. His skill is at the top of the craft.

landlocked sailor
11-08-2011, 09:56 PM
Thanks Lew. We were only trailing her about 15' astern, not nearly enough clearly. I am looking forward to some photos; that would be a great help. Here are a couple shots from our recent Chesapeake cruise: the little island on Broad Creek off the Magothy River and the Schooner Sultana ghosting along on the Chester River.
http://db.tt/Noz9wY6j
http://db.tt/3XCmo22Y
Rick

Tom Lathrop
11-09-2011, 12:21 AM
Hi Rick,

I should take a poke in here I guess. I can tow my 8' dinghy at 14 or more but can readily see that the hull shape yours will not be at all happy at more than 5. Actually we almost never need the dinghy for our cruising but in more populated areas like the Chesapeake, it makes more sense.

I think the most practical solution is some form of the davit idea suggested by Erster, Lew and others. I'd place it to one side against the aft bulkhead and let in through the cabintop. Only enough needs to stick out the top to allow easy insertion of the working davit or mount a winch, if that proves the best place for it. Aluminum will be plenty strong enough for such a light load and having the davit on one side minimizes the cantilever arm. The bent portion can be obtained from any fabricator who makes "T" tops and the like. The davit should be light enough to be easily lifted from its chocks on the cabintop and inserted in the lower tube. An HDPE collar on the lower tube and davit will serve as rotating bearings (one could be aluminum) and a small trailer or similar winch does the work. A guiding handle on the davit or a control line on the end of the davit prevents the thing swinging about while in use. Mounting of the winch depends on where it works best. A pair of sister hooks connects the lift line to the winch line for easy rigging.

The cabintop is plenty strong enough for walking on. Even mine with thinner ply than yours gets walked on when cleaning. The stability of the boat should not be a problem for either lifting the dinghy or rolling although there will be some effect. Because of an increase in moment of inertia, it might even significantly increase the roll period. Of course, all chocks for the dinghy and the davit need to be fixed over internal beam locations.

A mast is certainly shippy looking and may provide for a riding sail but the negatives outweigh the positives on a small boat, I think.

With all these brains working on the problem, a good solution should be possible and you need a winter project.

landlocked sailor
11-09-2011, 12:34 PM
Thanks Tom. What do you think about mounting the base on the side deck near the aft bulkhead and adding a reinforcing collar at the cabin top? This way I wouldn't have to penetrate the top. I am not sure what you mean by HDPE collars though. You're right, I do need a winter project :p. Rick

Tom Lathrop
11-09-2011, 03:02 PM
Structurally, that would work but I'd think it might look a bit awkward. Erster's comment sounds better and the lower tube would not have to go down further than the deck coaming. There would be no great problem to run it through the top in the aft overhang though. Filling the interior circumference area of the hole with epoxy would insure water tightness and no flange would be needed. plus the lower tube would then be against the bulkhead and less exposed and less visible.

Erster, I just got a call from a BJ25.5 builder in Wilmington who told me your cruiser had been bought. Now you can get busy on the next one! I'm sure Linda is spoiled and will want another.

HDPE is high density polyethlene and is available in cutting boards or as raw stock. Other hard plastics like Delrin, ABS or Polypropylene would also work fine.

Phil Y
11-09-2011, 04:04 PM
If you carry a small air compressor on board you could fit some airtight tanks down below. Sink the mothership, place the dinghy over the cabin top, then refloat using the compressed air. Simple.

Tom Lathrop
11-09-2011, 04:18 PM
If you carry a small air compressor on board you could fit some airtight tanks down below. Sink the mothership, place the dinghy over the cabin top, then refloat using the compressed air. Simple.

Sounds great at first glance but since you are in the antipodes, wouldn't the boat float keel up with the dinghy under the water? Archimedes was from the northern hemisphere and his principles might not work the same down there.

landlocked sailor
11-10-2011, 12:04 AM
Erster, I have read your suggestion half a dozen times and just cannot visualize what you are suggesting. Rick

Hwyl
11-10-2011, 07:39 AM
I'd say you did pretty good drawing that Mike. I still like my temporary ramp over the cockpit though.

Hwyl
11-10-2011, 07:49 AM
I suppose if I want to do it my way, I should design and build my own. I do like those Lathrop designed boats though, although 18 knots is a little speedy for this blowboater

landlocked sailor
11-10-2011, 07:59 AM
Here is one commercially available model
http://db.tt/AN41Lrqh
But at 3 grand delivered a bit on the absurd side: http://www.katomarine.com/powerdavits-standpipe.htm
I have to figure out how to make the sleeve and HDPE parts.
Rick

snow(Alan H)
11-10-2011, 08:01 AM
By the way, I routinely tow at eleven or twelve knots. The trick there is a VERY LONG painter. You see guys towing at high speed all the time up here. The bow eye in the dinghy needs to be down low, and the painter needs to be very long if you intend to tow over hull speed. Some boats do tow better than others, but it should not be that hard to figure out how to rig to do it. Towing with an outboard would seem to complicate things, I admit.

Examples below from another posting on the forum showing some high speed towing

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/ScreenShot2011-11-11at20231AM.png;

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/ScreenShot2011-11-11at21030AM.png

Lew Barrett
11-10-2011, 11:03 AM
I was earlier going to post that the dinghy thingy is one of life's vexing problems when it comes to mating them to a small cruising boat.
Erster's point about scale makes sense; a lot of the solutions being proposed work fine on a slightly bigger boat, maybe not as attractive on a smaller one.

I would certainly do a little more experimenting with towing, bearing in mind Tom's warning that some boats tow better than others. The hard bottom rubber boats do pretty well in this regard, maybe because they are so buoyant (and if they fill a bit, who cares?) but you might try something like Alan has pictured just to see if it will work, keeping in mind the notion of various harnesses to put the towed boat where you want it. I concur with Mike's point about how clumsy that can be if you end up having to tow two separate boats home at the end of a weekend. However, here where distances are long, it is very, very common to see small boats being towed hundreds of miles, though they are more rarely beautiful handmade sweethearts like yours.

Meanwhile I will try to add to Erster's picture gallery in the next day or two. Have I said how sweet a (set of) boats you have there? It's easy to see the appeal!

Dale Genther
11-10-2011, 01:34 PM
I've been following this thread with interest as I have a similar prpblem to the one landlocked sailer has. I want to store my lapstrake dingy on the cabintop of my Chesapeake Bay Deadrise. The solution that I like the best is the on in post #48, the Kato lifting boom. But I agree the price is way too much. So, since this is a wooden booat froum, how about some ideas/designs for a similar boom made of wood?

landlocked sailor
11-11-2011, 03:18 AM
Thanks again for all your input & ideas everybody. This has turned out to be an interesting & enlightening discourse; my initial plan was a tabernacled mast on the cabin top forward of the dinghy, an overly complicated solution I now realize. Then Ian's idea for an aft mast had me convinced. Now, I like the single tabernacle scheme the best. Am I suggestive & fickle or what?. I wonder what other pretty idea will catch my wandering eye next. Seriously, an alluminum pole on the aft bulkhead with a detachable davit really seems like an elegant and simple solution. As far a transportin the dink over the road, she fits neatly in the back of the towing vehicle; a 2000 Ford Expedition, though her bow does come up un the center console a bit. Rick

landlocked sailor
11-11-2011, 09:40 AM
Nothing to add except this is the first thread I have ever started that went to two pages! Rick

landlocked sailor
11-11-2011, 09:49 AM
Hardware Catalog1.pub
Something like this might work to secure the base pipe to the cabin top.Rick

landlocked sailor
11-11-2011, 09:54 AM
I keep screwing this up. Maybe this will work. Rickhttp://www.ballentinesboatshop.com/PDF%20BBS/BBS%20Hardware%20Catalog.pdf

landlocked sailor
11-11-2011, 10:35 AM
Thanks erster. I was trying to post a picture of the bronze mast partner/gate they sell as a prototype of a support at the cabin top. I just recently was educated how to post pics from my iPad but it would not work from the website. Rick

Tom Lathrop
11-11-2011, 02:06 PM
If I had to pay those prices for hardware, I'd have only one boat instead of an indeterminate number of them. On second thought, maybe that's good thing. That mast gate is certainly strong enough but what have you got to attach it to that matches the strength? Also, the angle is wrong for the curved edge of the top. If you want to use that mounting method, it is not so difficult to mold your own FG bracket hardware to your own needs.

landlocked sailor
11-12-2011, 12:17 AM
erster, sorry about that; no wonder I could not get the link to come up.
Tom, I agree. I was just using that as an example for clarity; something homebrewed would be preferable. I have to measure directly, but it looks like I only have about 3" of rooftop aft of the aft bulkhead. I don't know how large a diameter of tube would be appropriate. Rick

snow(Alan H)
11-12-2011, 12:57 AM
Ok - at one of the local marinas yesterday & I checked out a set-up that I had previously seen & had thought - 'that might be the of interest' - see pix below.
Alan

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/IMG_4664.jpg;

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/IMG_4661.jpg;

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/IMG_4659.jpg;

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/IMG_4660.jpg;

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/IMG_4662.jpg;

http://i408.photobucket.com/albums/pp165/Alanh22/Alanh22A/IMG_4663.jpg

landlocked sailor
11-12-2011, 03:52 AM
Here is an interesting source: http://ezpull.net/ecf/index.php


http://ezpull.net/shop/media/ecom/prodlg/1EGSx.jpg

Lew Barrett
11-12-2011, 12:47 PM
That' a loooong arm!
A bit on 316 while we're here. (http://www.fanagalo.co.za/tech/tech_grade_316.htm)

My pictures later today without fail. Not that I think my set up is what the boat should get, but because it represents a very traditional approach to this problem.

Lew Barrett
11-12-2011, 09:29 PM
http://i240.photobucket.com/albums/ff76/LewBarrett/davit.jpg

I'm thinking that at this point this adds very little to this thread, but if it helps, that's good.

These are almost 73 years old now, which is some kind of testament to the staying power of steel and bronze. You can clearly see they are in two main parts, the upper piece that is the arm and the lower tube that receives it. Also visible is the hole that receives a pin after the upper arm is lifted into position.

About 15 years ago I took them down, cleaned them up, painted them and re-bedded the supporting hardware that holds it all together. That has held but I can see they need paint again. It's always annoying to me how I can ignore details like that until I take a closer look....or a picture! Using them is sort of entertaining in it's own right.

ChrisBen
11-12-2011, 09:48 PM
Thanks erster. I was trying to post a picture of the bronze mast partner/gate they sell as a prototype of a support at the cabin top. I just recently was educated how to post pics from my iPad but it would not work from the website. RickHere you go.
http://i143.photobucket.com/albums/r133/loki59/mastpartner2.jpg


http://i143.photobucket.com/albums/r133/loki59/28.gif

landlocked sailor
11-13-2011, 07:12 AM
Alan & Lew, thanks so much for taking the trouble to post the photos, they really help focus my thoughts. Lew, on the contrary, your set up looks like just about what I need. I will likely opt for aluminum, but the basics, including the retractable upper piece, are all there. Rick

landlocked sailor
11-13-2011, 08:19 AM
How about a couple layers of marine plywood well sealed in epoxy & painted; durable and sure takes care of the grain orientation issue. I have plenty of that. Rick

Lew Barrett
11-13-2011, 02:55 PM
My davits both land on teak pads,but they are hard to see in the photo. All the real bending stress is taken up by the fancy looking bronze fitting that is through bolted and reinforced right through the deck. It is undoubtedly a weak point, and requires a stout backing on the ceiling. I had to repair it when I got the boat. Roof penetrations something to try and avoid, but in my situation, that was the way they did it. I have it caulked so it doesn't leak, but it was dribbling when I got the boat.

Lew Barrett
11-13-2011, 07:39 PM
Mike, if I use the rubber ducky, there is no stress at all on the davits, and the nice little Monk boat up there becomes a great crab pot holder :D

Lew Barrett
11-13-2011, 10:56 PM
Haven't checked the price of King crabs, but they are surely delicious. But twenty eight bucks? I'll take lobster any day.

pipefitter
12-23-2011, 04:49 PM
Just took a quick look through this thread and I see what you need. I like Erster's idea with the flange bearing attached to the cabin top extending outward and the works mounted to the coaming or wherever it needs to go. In a demountable situation, the cabin top flange could even be hinged so as not to have to be hanging out over the cabin when not in use, but folded neatly and nearly flush atop the cabin and merely flipped down when needed. The davit itself could even be made in two pieces for more options regarding stowability and even shipping concerns if need be.

P.S. I really do appreciate the compliments from posters as to the quality of my work. Thank you, and Merry Christmas/happy holidays to all.

landlocked sailor
04-11-2012, 07:26 AM
This project is progressing; the cradle pieces are made and ready to install and I found a fabricator for the crane parts. Today's questions regard rigging the attachment points on the dinghy itself. Sound I lift from the gunwales or the keelson? If the latter, how to stabilize the dinghy athwart ships? Photos of anyone's set up are really appreciated. Rick