Our RIB davits. There has to be a better way!

[SteveK]

Steve, I'm open to suggestions but I'm having a hard time visualizing your concept. Do you mean fabricate a lifting bar except out of chain, pulled tight and down low in the dink and then attach the lifting blocks from the davit to points on the chain that are more directly under the davits?

I have a stainless cable, three points, inside bow, and two to transom eyes that are inside. the three join about 18 inches from transom to an eye that my single davit connects to. That cable lays on floor when not in use.

I am suggesting test the idea by tying your fore and aft chain together, use the same connection points. The davits will lift the assembly mostly level with floor of dink thus arriving closer to the davits

 

[psneeld]

If it comes to it and at any point there is the possibility of chafe..... Dyneema line or equivalent (cheapest I found is winch replacement line on Amazon for wire rope replacement) is strong enough and slippery as all get out so chafe to object or line is minimal.

Shawn, the 3 point attachment of Dyneema I had for the Albin dink I believe is/similar to what Steve is suggesting.

 

[boomerang]

I have a stainless cable, three points, inside bow, and two to transom eyes that are inside. the three join about 18 inches from transom to an eye that my single davit connects to. That cable lays on floor when not in use.

I am suggesting test the idea by tying your fore and aft chain together, use the same connection points. The davits will lift the assembly mostly level with floor of dink thus arriving closer to the davits

Thank you. I think I'll try just that! Your setup seems to be similar to the C-Level system that rslifkin brought to my attention. I want to keep my lifting point over the transom of the dink over the transom as much as possible because the dink already hangs dangerously close to the starboard rubrail and I have to be aware of it while docking. The setup you suggested would allow me to move the front lifting point aft, which is all I really need to accomplish anyway.

 

[boomerang]

If it comes to it and at any point there is the possibility of chafe..... Dyneema line or equivalent (cheapest I found is winch replacement line on Amazon for wire rope replacement) is strong enough and slippery as all get out so chafe to object or line is minimal.

Shawn, the 3 point attachment of Dyneema I had for the Albin dink I believe is/similar to what Steve is suggesting.

Yep, you are right! I forgot about your setup. If I recall, the lifting harness remained in the boat and you had it tuned to be picked up at a single lifting point and remain balanced. I need to go dig some pictures out.

 

[psneeld]

Yep, you are right! I forgot about your setup. If I recall, the lifting harness remained in the boat and you had it tuned to be picked up at a single lifting point and remain balanced. I need to go dig some pictures out.

I did chains at first, thinking clips could adjust the chain length till I got it right. Worked pretty well.

Chains still chafed so I switched to the winch rope... used it on the winch too as it was easy on the hands. By using the synthetic line... I tied it up at about the same length as the chains, then reknotted it several times to tweak it just right.

Took all afternoon of trial an effort, but to me it paid off.

Still think my original prototype was the best. It was like the bar you pull down over your head on a Ferris wheel that is a safety bar. For the dingy, it acted the same giving a solid hand hold to get in/out of the dink and stabilize it while in it. Unlike the video, it was one continuous bar that resembled davits to hang the boat but continued in between to form the safety bar, provide stiffness and multiple places to add the hangars to hang the dink from.

Here was my prototype.... by far the quickest launch/retrieve, ease of entry, convenience of keeping things in dink and add/subtract gear at convenient height, easy to secure from swing and boarding seas (if a tad higher as the prototype sagged)..... If I had to do it all over again, the only davit system would be this one with a stronger and professionally fabricated. Forgot, nice that if partially deployed the swim platform is completely usable and safe as the dink acts as a barrier.

 

[luna]

One of your biggest problems is that the lift points on the tender do not vertically align with the distance between the davits. To be easy to use the blocks should hang vertical, just like any other crane.

That means you need to change the pick up points on the tender, as you are not moving the davits.

To do this you can construct a pick up bar that connects to the tender, down low near the floor level and runs from the transom to the existing forward pick up point, so that means the bar is about 6' long.
Along the length of this bar you then determine the new locations where the block connects (no chains req'd) so that the tender is located across the beam of the mother ship correctly.

I would construct a working mock up of this bar out of 2 - 2x4s and plywood so that I could get the geometry right and then build the final product out of something like 1.25" x 1.25" x .25" Aluminum tube and . 25" plate or some clear kiln dried Douglas Fir. Finish on either is up to you.
Your tender likely weighs about 200 lbs, so as long as you leave the Garboard Drain Plug out and don't get pooped, you should be fine.

A couple of notes:

- The lower you mount the pick up bar (eg. really close to the floor) the less stable the tender is when lifting.

- The pick up bar could be left in place while you use the tender or removable without tools, your choice.

- Once you get the tender to the fully raised position where the blocks are in contact with the tubes I would fashion a mechanism to stop the tender from swinging or rocking by pinning a plate connected to the transom of the tender to another plate or two connected to the davit. No ropes or racket straps req'd.

 

[firehoser75]

I found that a 4 stroke Nissan 6hp engine would plane our (RIB) dinghy with just me in it, but would not plane it when the wife was also aboard. We switched to a Yamaha 8hp 2 stroke, and that little unit planed the dinghy fine with both of us aboard and groceries. When alone with the 8HP, the dinghy clipped along at about 15 knots, which was fast enough for me. The Yamaha 8 was quite a bit lighter in weight than even the 6 hp and certainly a lot lighter than the 9.9HP's. Mixing the oil with the fuel was not a big deal, but finding a well maintained 2 stroke may be a problem.

 

[boomerang]

A follow-up to this thread and a big thank you for everyone's input regarding our dingy davit lifting setup. After adding an eyebolt centered on the transom and a piece of chain connecting the bow eye to the transom eye and then playing around with different lifting points , I'm finally satisfied with the system. I don't have too much of an issue with the chain because we just unclip the 4 carabiner hooks and leave everything behind when we're puttering around in the rib. I'll probably turn the 2 transom eyes back around so they're facing aft again, which will allow the whole thing to come forward (relative to the RIB) a few more inches but the main thing is the back of the dink isn't anywhere near close to the rubrail as it used to be, which is a load off of my mind when docking. As suggested early in the thread, I'm going to use a piece of carpet or something and attach it to the forward davit pads so they don't chafe the inboard tube when it's pulled up high and tight (as evidenced by the black rub marks on the tube in one of the pictures). I do still need to get some straps ordered to secure the thing from swinging but the setup is 100% better than it was when I reached out for help. I just wasn't sure how the system was supposed to perform or be setup and everyone's suggestions were much appreciated.
I also picked up a single cylinder 6hp Tohatsu outboard this past weekend and while it doesn't jump on plane with 2 people like it did with the 9.8 hp, the tradeoff was well worth it in weight savings and manageability with regards to me being able to load and offload the motor by myself. The 2 cylinder was just too awkward and heavy for me to be comfortable doing that plus it was a lot more weight hanging on the davits while underway with the motor mounted on the transom. I'm still deciding where I want to mount a bracket to store the motor while cruising in rough seas; I'm leaning towards on the transom of the boat where it'll be easier to load/offload to/from the RIB but it'll also be easier to be stolen , if a bad guy gets the hankering to swipe it. I'll probably add a motor lock and if that doesn't work, I'll resort to using lead (I actually had to go that route years ago ,unfortunately).
Please excuse the dirty dink pics. I haven't gotten around to the spring cleanup yet.

 

[SteveK]

Good for you for getting it done to your satisfaction.
May I ask why the outboard have to be removed, is it because of how the chain on transom is located which would be in the way or your preference to remove?

 

[boomerang]

It probably doesn't have to be removed now that we have a lighter motor but the davits , especially the back one with the weight of the motor, really put a lot of strain on the mount pads going through the deck. I can see evidence of stress cracking and don't want moisture getting into the core. The Edson davits are about 4' long and then they have some kind of an Edson extension mounting bracket under them allowing them to stick out farther yet. Hanging 4' out and and the load being easily over 100lbs on each one, the force on the deck pads just makes me uncomfortable. I'd really would've liked to see a different mount method and even though the fiberglass has been beefed up on the underside, it still seems to be under too much strain to me. But I do tend to overthink and worry too much about things most of the time...

 

[boomerang]

Here's what the davit mounting bases and the underside look like. You cant really tell but the underside has been beefed up with 3/4" ply and woven mat. Everything will probably be removed later this year for topside repainting and I'm seriously contemplating adding a reinforcement bracket under the davits that would bolt to the transom and give some vertical support or perhaps extend the footprint of the horizontal bases to spread the strain out over more area, either of which idea involves me having to remove the headliner or the not-easily removable wood panel on the aft wall to gain access to the transom.

 

[SteveK]

Glad you showed me the bottom. I suggest on the next haul out that you replace those washers with a full plate aluminium or stainless. Not urgent. If you don't it will slowly wear a hole in the bottom thru the mat and ply. JMO

The reason I asked is the top setup looked sturdy enough to carry the outboard if there is no up/down constent movement.

 

[KnotYet]

As SteveK suggests above, a backing plate will make it as bulletproof as it can be.
1/4" aluminum is a fine choice, as large as will fit.

 

[luna]

Boomerang.

I see that you chose to use a chain instead of a solid bar to pick up the front end of the tender.
Now that you know where to pick it up, consider fabricating a pick up bar so that you can lift it high enough to engage the davit mounted stabilization pads correctly.

Depending on the geometry, a short bar may well be the solution for the transom as well. The chain should only run vertical, if possible.

I don't think there is a need to wait for a haul out to address the improvement to the davits connection. Isn't the underside of the davit to boat connection accessed from the aft cabin's overhead?

 

[psneeld]

Here's what the davit mounting bases and the underside look like. You cant really tell but the underside has been beefed up with 3/4" ply and woven mat. Everything will probably be removed later this year for topside repainting and I'm seriously contemplating adding a reinforcement bracket under the davits that would bolt to the transom and give some vertical support or perhaps extend the footprint of the horizontal bases to spread the strain out over more area, either of which idea involves me having to remove the headliner or the not-easily removable wood panel on the aft wall to gain access to the transom.

Agree an L shaped bracket as backing plate and bolted to the transom would be the ticket if the transom is beefy enough.

If not as stiff as you want, maybe stiffen those sections of the transom?

If stiffening looks difficult, there is (though a PIA) temporary arms or cables that could be used from the aft cabin top to the tops of the brackets. They would be removable and just used underway or underway in certain conditions.

 

[Shrew]

If not a backing plate, you could still easily get significantly larger washers. When the washer is relatively the same size as the nut or bolt, there is no distribution going on.