MS 430 Aft Cabin, Dinghy and Davits...

Hi all,

We have a 2005 Mainship 430 aft cabin trawler. We’re looking at hard bottom dinghy options. While we have an idea of the type of dinghy we want, I am more interested to see how others with the MS 430 Trawler have accommodated their dinghy and what manual (non electric) davits they used.

We’re thinking of a dinghy that weighs around 400 pounds w/ motor. Does anyone have a dinghy on their transom that weighs this much? What is your davits system and have you seen any indicators of stress on the transom? We are thinking of a manual davit system.

I am interested to see if others have had any stress issues (transom or swim platform supports) with putting a dinghy of this size on their swim platform? Did you need to beef up the original under platform brackets?

What did you do to limit the lateral movement?

Thanks,

JimL

I have the same boat. I have a AB10 VSX hard bottom. Weighs around 450lbs wet. I installed a Jatco 600 lb lift. It is the winch model that can load from port or stb. It comes with the underwater support brackets that support most of the weight. There is very little stress on the platform. I added tie down eyes on the corner of the platform to strap it down. I upgraded to the SS winch. Cost is about $7K. Very nice unit. They have a website.

Thanks Vacser,

Did you do the installation or was it installed by a professional? Do you have any pics of the under swim platform support structure? It appears the bulk of the weight of the 450 lbs is toward the middle to aft areas of the swim platform. Have you experienced any issues with the twin platform or transom?

Thanks,

Jim

Jim, I did the install myself. Took about 10 hours. I have only had the lift since December 1, but I have had no problems. Loads and unloads very easy. I have 4 photo's I will try and post.

Vascer,

Thanks for posting the pics and the web site. I looked at the web site and it looks like there are two struts that sport the system, other than the hardware on the swim platform. Is there a lot of weight on the swim platform or is it transmitted to the transom via the struts? (I'm asking because my swim platform was rebuilt last winter $6K and I don't want to do that again anytime soon.)

Also, when cruising, have you noticed a change in how the boat handles in calm water, docking or in heavy seas?

Thanks,

Jim

Jim, our swim platform is similar to yours, and we also have the Jatco Trillogy system vacser has. Ours is probably rated at 450 or maybe 600 lbs (I kinda forget), and we've had it for about 11 years now (from memory). Our swim platform is supported by 4 struts. The davit is (now) also supported by two additional struts to the transom, underwater.

The earlier dinghy and motor weight about 175 lbs total; I did the installation.

The current dinghy and motor weigh around 260 lbs total... and we added the two transom struts as we prepared for the heavier weight. I had our yard do that part of the installation. Those two struts on ours are at a much greater down-angle than vacser's, as we apparently have a much deeper V hull. That may add some limitations to the weight you can carry...

The Jatco engineer's name is Joe Trillo. If you talk with him, he'll advise what you need.

Have you thought about lifting the dinghy to your aft cabin "boat deck"? There can be some issues with carrying a dinghy on the swim platform... not insurmountable, and there are advantages, too... but then you've actually got a "boat deck" possibility, whereas we didn't have that kind of choice...

-Chris

Jim, It seems to me that most the weight is transferred to the bottom of the transom. Joe who owns Jatco is a very knowledgeable man, he can probably give you percentages of weight distribution. I have only had the boat out a few times since install and all seems normal. My thought on the extra weight is that I can always drain some of my aft water tank, 125 gallons/1000 lbs if I feel to heavy. I had my platform redone also with Nida core just for this reason. I have gotten in the dinghy on the lift and walked around looking for flex, rock solid. Jimmy

I don't notice any impact on the mother ship from the additional weight aft. The outboard weight adds a very slight degree of list on that side, not enough to cause me any concern.

The main thing I'd ask Joe about is the angle of the down struts. Ours are at a much greater angle, maybe 45-50 degrees compared to your (guessing here) 25-30 degrees or so (??)... and I think that angle will influence overall capacity.

Something I didn't include earlier: bringing our dinghy up onto the "pontoons" is pretty much a one-handed job with the manual winch. Not really much effort required...

-Chris

Jimmy & Chris and others,

I will call the Joe at Jatco. Putting the dink on the aft or fwd cabin decks are not options for a multitude of reasons, but thanks for the suggestions.

I think the concern is the weight of the davits and dink on the swim platform that ultimately stresses the transom is the concern. I have been trying to engage with other MS 430 aft cabin owners on their arrangements with success. The struts that support the swim platform are thru bolted thru the transom. Putting another less than 500 pounds may result in stress on the transom or may not. It would be great to know what the design specs of the transom and the swim platform were when the MS trawlers were designed and made.

I went to the NYC boat show this weekend and saw a few dinks under 450 lbs that would work - side console, AL hull, and a 20hp motor. All had good lifting hooks. Only one marina was there that would deal with the davits and the recommendation was St Croix.

Still looking and learning.

For those who have cruised the Caribbean and ICW, do you recommend a tiller drive or a center console? We are my wife and I with foldable bikes and love to explore and dive.

Thanks as always for your input.

Jim

jimL said:

It would be great to know what the design specs of the transom and the swim platform were when the MS trawlers were designed and made.

For those who have cruised the Caribbean and ICW, do you recommend a tiller drive or a center console? We are my wife and I with foldable bikes and love to explore and dive.

Click to expand...

Our boat builder, related to Mainship, told me our 4-strut swim platform was designed for 500-lbs of LIVE weight, not dead weight. Adding additional support direct from the davit system seemed prudent.. so we have a significant margin. Especially since ours is a cantilevered installation, so we can walk between boat and dinghy. (Don't remember if I mentioned that before.)

FWIW, there's a 430 near us here in the marina in Charleston named Kismet with a lifting davit system mounted on their swim platform. Not on the Mainship transom. I don't recognize a maker's name, but imagine two tall (angle "iron," painted white) davits with block and tackle. The arms are about a foot higher than the Mainship transom. That system lifts the dinghy much higher than our swim platform mount, which likely alleviates wake issues when slowing down. Doesn't look like it solves issues with cross-tying stern lines, but it also doesn't look like it adds complications for that.

One of their davits (port side, furthest from swim platform door) is connected to the Mainship transom at the top so that would add some support. I suspect they only added that brace to one davit because the other would interfere with access to the swim platform... although that would seem solvable with a quick attach/detach connection.

In any case, that brace also complicates transit across their whole swim platform; the owner is using a ladder on the side of the boat to get to/from the floating docks.

I prefer wheel steering... but we use tiller steering. That's more about budget than preference or weight.

-Chris

Hi all,

I'm getting closer to picking out the dink, motor and davit system. I am thinking about a Seawise manual davit system that pivots the dink on the swimplatforms on it's port side creating a 90 degree vertical angle.

I have a really dumb question for those who store their drinks on the side. What happens to the battery and fuel tank? I just saw the Seawise demo video and it appears the dink in the video had the battery in the boat because the person adjusted the motor tilt while the dink was on it's side. Also, in the pic you can see a fuel tank. I would have thought the fuel and battery acid would leak out.

What are the best and safest practices?

Hydraulic Boat Davit System - Sea Wise Davit System

Thanks,

Jim

I have a Seawise davit system on my boat with an electric start 15 HP OB. The start battery is a sealed battery, so no spillage. I usually take the tank out because I don't have it fastened down. If I get aroiund to fastening the tank down, I would orient the tank so the fill cap is on the high side when the dinghy is lifted up on its side.

Mu dinghy lived on its Seawise for several years before I got it. The battery is AGM, so no issues. The fuel tank is integral, in the bow, so if yours is similar, Caribe and other mfgrs route the vent hose around the locker above the tank so that there is no spillage when on its side.
You will need to pump the bilge before tipping up, as there is no other way to get rid of any bilgewater.

I heard recently that West Marine gets some of their dinghies from AB. Does anyone know where WM gets their dinghies from?

Jim

We had a Seawise davit on a previous boat. Loved it. Great support from the company. We had an AGM battery and an L shaped portable gas tank. The tank was mounted so that when the dinghy was tipped up the bottom of the L was down. That way when you tip the dinghy the gas flows into the bottom of the L and the filler cap is at the top and no gas is around the cap due to the gas running into the bottlm of the L. Hope this makes sense.