Mainship 390 Dinghy Davit advice needed...

Mainship 390 Dingy Davit advice needed... looking to upgrade from the Weaver Snap Davits to something I can keep the outboard on and store my Mercury 310 RIB and 9.9 Merc 2 stroke horizontally. Looking at the Hurley H20 system or something that lifts it up to the bridge deck height (no idea what brand). I have a 2001, the last year of the aluminum bridgedeck railings. Any thoughts would be appreciated, I'm getting too old to dangle 70 lb motors off the transom!

Whatever you use be sure that it doesn't require more than 25lb lifting force, or is electric powered.

Bob809 said:

Mainship 390 Dingy Davit advice needed... looking to upgrade from the Weaver Snap Davits to something I can keep the outboard on and store my Mercury 310 RIB and 9.9 Merc 2 stroke horizontally. Looking at the Hurley H20 system or something that lifts it up to the bridge deck height (no idea what brand). I have a 2001, the last year of the aluminum bridgedeck railings. Any thoughts would be appreciated, I'm getting too old to dangle 70 lb motors off the transom!

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I would suggest a swivel for the outboard and leave the weavers

https://seawisemarine.com/ When we purchased our 390 I put a set of Davits on the bridge deck, I do not recommend this we abandoned the idea after a year and put a set of weavers on the swim platform. the stresses up top are are far greater than the rail is designed for.

When we were looking at 390s, our plan was to have a lift like this custom made that put the dinghy up level with the aft deck so it was handy and secure, but out of direct line of sight from both the fly bridge and the cockpit.

HeadedToTexas said:

When we were looking at 390s, our plan was to have a lift like this custom made that put the dinghy up level with the aft deck so it was handy and secure, but out of direct line of sight from both the fly bridge and the cockpit.

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The only downside to that is the 390 has a walkthrough Transom and with the weaver and swivel you can still use the swim platform and the dingy is clear of the Water, even in Large seas

Here are some better pictures to illustrate my idea, or rather, the idea I borrowed from others!

This is disturbing news, as I was leaning this way to get full dive platform use. Can you share the particulars of your bridge deck stresses?

I have the standard davits for my dinghy as I do not leave my 5hp Tohatsu on it when I travel however, I would definitely be interested in Seawise System with a swivel on the Engine if it was 9.9hp. I do believe that the swim platform is much stronger on MS390s than the Bridge.
good luck,

We put a SeaWise davit system on a previous boat. It was wonderful. We could launch in one minute and recover in two minutes. The motor stays attached and stows upright over the swim platform. It does block one side of the platform but the other side is clear. We will be putting one on our next boat most likely.

DrissZougari said:

I have the standard davits for my dinghy as I do not leave my 5hp Tohatsu on it when I travel however, I would definitely be interested in Seawise System with a swivel on the Engine if it was 9.9hp. I do believe that the swim platform is much stronger on MS390s than the Bridge.
good luck,

View attachment 115579

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Is that a single point of attachment for inflatable/outboard? Or maybe I cannot see part of the rig in the photo?

Bob809 said:

This is disturbing news, as I was leaning this way to get full dive platform use. Can you share the particulars of your bridge deck stresses?

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I think you were referring to my post re Davits up top. if not I apologize, if yes the reasons were the Rail is not as stout as it looks the rail is not designed for the stresses of a dingy hanging off the rail. the rail is only screwed Not through bolted into the Bridge deck. Even strapping the dingy side ways and tight to the Rail, in a good sea the whole unit moves, I had a very expensive set of Fore spar Davits with cross support and it was only going to be a matter of time before disaster was going to strike. If you research those that have installed them successfully you will find that people with a 390 or 350 have done some substantial work beefing up the rail, and in all cases that I have seen protrude into living space up on the aft deck and down in the cockpit. Having the weavers, (Mine are a knock off as you have to have a 6" to 8" standoff because of the curve of the swim platform. work very well no stress and with the seawise allow for the engine to stay on, and is easy to Launch. we still use the transom door and swim platform. when we are at a dock I lower the dingy to allow for full visibility when in the cockpit.

Hello all,

I can shed some light on the davits on the Mainship 390 MASCOT. I was the one who designed it and had it custom made. I must confess I saw something similar on another 390 before I did this one. I no longer have this boat but did adapt the design onto our American Tug also named MASCOT. The stresses are not too much. The pull on the cable was somewhere in the neighborhood of 500# with the dinghy in the picture which weighed less than 250#. The overhead is plenty strong. Just think, would you be scared to have 2 people standing up there? The boat is designed for at least that. When in the 'UP' position, all the forces are shear forces on the transom mounts which had 6 1/4" bolts on each side. Plenty strong.

Oops! Looks like I need to change my picture! No longer have that boat either!

MASCOT

it is a single point attachment to engine bracket.
The engine will swivel as you lift the dinghy up.

Mascot said:

I can shed some light on the davits on the Mainship 390 MASCOT. I was the one who designed it and had it custom made.

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Great looking and very functional setup, Mascot. I plan to apply that concept to my Mariner 37 as the St. Croix davits both leave the dinghy in the way and are ready for replacement. Can you share who custom made it for you?

I used a fabricator in Massachusetts who is no longer in business. I provided him with dimensioned sketches and a template to work from. I started by making a template from 1/4" plywood to get the geometry right. You want the dinghy to settle in the water beside the swim platform, not on top of it. On the Mainship, the vertical part of the arms are straight. On my American Tug, they needed to be more of a ? shape because the overhead does not go as far back as on the Mainship. Your Mariner might be different still. Once that was done, the rest of the dimensions were easy to calculate. The arms are angled in at the tips so the attachment points at the transom are wider apart than at the tips where the dinghy attaches. The short attachment cables / bridle are stainless that I fabricated at West Marine. Most stores have a small work bench with all the tools to swage thimbles at the ends. I used saddle clamps to adjust the cables for the mock-up then made permanent cables using crimp swage fittings. The winch is a standard 12V ATV type located under the overhead.

I wish I could simply tell you to go to XYZ fabricators and he will take care of you but that's not the case.

MASCOT

There’s an off-the-shelf davit that can be configured similarly to Mascot’s called the Dinghy Butler. The mounting pads can be bolted either to the transom, directly to the swim platform or to custom brackets under the swim platform (as I did). The builder is very flexible and will help customize it to your specs. Available in cast aluminum or stainless at a lower price point than models with bigger name recognition and similar lifting capacity. I’m installing one on our 44 sundeck to handle a 550–lb dink.

The magic of the Mascot design is that it puts the dinghy comfortably above the swim platform to allow line of sight out of the cockpit, access to the swim platform, and dock access off the swim platform. And unlike a crane that lifts the dinghy onto the boat deck, the Mascot design does not occupy deck space. Win-win.

I would agree that since all boats have subtly different geometries, some engineering is part of the job. Thanks Mascot.

I found dinghy caddie to work better than the sea wise on my 400. Less attachment points. I have Inmar 11 RIB with console and 20hp. Just under 400 pounds. No problem. Have gone over 1000 miles with it back there. I can also still board swim platform and I leave transom door open all the time. Only issue for 390 is transom door is in the center. 400 door is to stb side.
https://dinghycaddy.com/Products

HeadedToTexas said:

The magic of the Mascot design is that it puts the dinghy comfortably above the swim platform to allow line of sight out of the cockpit, access to the swim platform, and dock access off the swim platform. And unlike a crane that lifts the dinghy onto the boat deck, the Mascot design does not occupy deck space. Win-win.

I would agree that since all boats have subtly different geometries, some engineering is part of the job. Thanks Mascot.

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Not sure if you were referring to my post but I may have muddied the waters with photos of my swim platform install. Just tried to note that, for those not wanting a one-off, there are semi-custom options available—like the Dinghy Butler—that will bolt to the transom and carry the dink plenty high. Sorry if I wasn’t clear.

HeadedToTexas said:

Here are some better pictures to illustrate my idea, or rather, the idea I borrowed from others!

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We have been actively trying to find SOMEONE who can fashion the davit system that is illustrated here, OR, someone who has some drawings of the actual design. So far, all the fabricators I have approached are not willing to take on the project without design drawings. I only have the same collection of pictures that have been shared here.

We are highly motivated if anyone can point us to a vendor for this particular solution.

Ray of Shellerina [.com] MS 390

Dingy davit

I have a similar setup, jgreene69@tampabay.rr.com
I can send you how I did mine (custom built)

Weaver Leaver

Have you looked into the weaver leaver? Keep existing brackets and add the Leaver to hold the engine. You will have to rig a pulley system or electric winch to pull the boat up. It’s probably the most inexpensive way to go from what you have now.

Tim said:

Have you looked into the weaver leaver? Keep existing brackets and add the Leaver to hold the engine.

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Just happened to see this Weaver Leaver today on Craigslist, SE Connecticut

https://newlondon.craigslist.org/search/bpa?query=weaver&purveyor-input=all

Rob

Bob809 said:

Mainship 390 Dingy Davit advice needed... looking to upgrade from the Weaver Snap Davits to something I can keep the outboard on and store my Mercury 310 RIB and 9.9 Merc 2 stroke horizontally. Looking at the Hurley H20 system or something that lifts it up to the bridge deck height (no idea what brand). I have a 2001, the last year of the aluminum bridgedeck railings. Any thoughts would be appreciated, I'm getting too old to dangle 70 lb motors off the transom!

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No, to all the above. Check out Rothskelly davits. The 9.9 o/b can stay attached to the skiff, you can launch in about 30 seconds, and re-attach in about the same, and then simply use a 3 or 4-part tackle to haul it out of the water to get underway. We got rid of the Weaver clips for this and it works so much better.

Check out Rothskelly Davit systems

Bob809 said:

Mainship 390 Dingy Davit advice needed... looking to upgrade from the Weaver Snap Davits to something I can keep the outboard on and store my Mercury 310 RIB and 9.9 Merc 2 stroke horizontally. Looking at the Hurley H20 system or something that lifts it up to the bridge deck height (no idea what brand). I have a 2001, the last year of the aluminum bridgedeck railings. Any thoughts would be appreciated, I'm getting too old to dangle 70 lb motors off the transom!

Click to expand...

Look at the Rothskelly davit systems. You can pull the dinghy up out of the water with ob attached. It's mounted on the swim step, but can be mounted to allow maneuvering around it, and is very fast and convenient. We replaced our Weaver Snaps, and the GB boom to aft cabin roof cradle, with it and are very pleased. Same size RIB and ob as you are talking about.

jgreene69 said:

I have a similar setup, jgreene69@tampabay.rr.com
I can send you how I did mine (custom built)

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Email on its way, J. Thank you.

Blue Tortuga said:

I found dinghy caddie to work better than the sea wise on my 400. Less attachment points. I have Inmar 11 RIB with console and 20hp. Just under 400 pounds. No problem. Have gone over 1000 miles with it back there. I can also still board swim platform and I leave transom door open all the time. Only issue for 390 is transom door is in the center. 400 door is to stb side.
https://dinghycaddy.com/Products

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These always have to covered or Dink will fill with water

Cartouche said:

These always have to covered or Dink will fill with water

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No, I put another drain plug in the transom corner near the tube. Just set the chains up for a slight slope aft.