Dinghy lift

[Tireless]

Viper,

Can I assume from what you are saying that these failures are on the tongue/winch assembly arm forward of the front knuckle. If that is the case, was the failure do to water/waves striking the bow of the dinghy and stressing out the arm till it gave way, or are the welds or joints failing due to downward force as a result of boat movement. Having said that, there are bolts at the knuckles that are required to be torqued properly, and checked periodically to spec, (220 ft/lbs). I can see how that would fail if not monitored. Could this be an issue?

I assume that your comments in general should be taken into consideration when purchasing any davit system, but, I need to drill down on the issues relative to the Sea Weed system that I have. How many events have you seen in your experience.

I know that they have sold hundreds of these systems over the years in the US and Canada. Would be interesting to find out from fellow Sea Weed owners on this forum what there experience has been.

Viper I value your opinion as always. Thank you.

[Viper]

Source of the post ....saying that these failures are on the tongue/winch assembly arm forward of the front knuckle. If that is the case, was the failure do to water/waves striking the bow of the dinghy and stressing out the arm till it gave way, or are the welds or joints failing due to downward force as a result of boat movement......

Yes a couple at the tongue, one was a welded joint and one was a pivoting adjustable tongue. The other failures were other adjustable arms at the pivot points. I suspect the failures are due to the downward and upward cycles and the heavy loads associated with that. I can't comment on whether they were torqued properly as I come in after the fact.

Source of the post.....I assume that your comments in general should be taken into consideration when purchasing any
davit system, but, I need to drill down on the issues relative to the Sea Weed system that I have. How many events have you seen in your experience.....

Of course there are considerations with every davit/lift system but some are built way beefier than others, that comes with a price tag though. I certainly wouldn't be worried about an arm breaking away from a FreedomLift or TNT but they do have other other maintenance considerations as would any hydraulic system.

I've dealt with a handful of structural failures. Been around a few different types; manual, electric, and hydraulic and the only ones I personally have had to deal with structural failures have been the Sea Weed. I know other guys have dealt with the same but I don't know why or how many. I suspect though that the why is related to loading stress. By structural I'm referring here to the davit/lift. Of course any davit/lift can compromise the vessel's structure if not installed or speced properly. I also think that when I get called they're out of warranty cases otherwise they'd be contacting Sea Weed first or Rudy as he has installed many units.

Source of the post .....Would be interesting to find out from fellow Sea Weed owners on this forum what there experience has been.....

I agree, it would be good know. On average they're probably a good unit for the price point but I can't endorse them based on my particular history.

[Pete]

Source of the post

After having my swim platform examined by a fiberglass guy for stability, I installed it myself using a 6 mm poly template I made from the previous boats installation. There is more to this than just drilling holes for bolts and backing plates. I oversized all the holes and filled with epoxy prior to drilling the required holes for bolts. This was done to prevent water intrusion into the balsa core in the swim platform. I also beefed it up by using a two large 1/4" thick marine aluminum plates under the three points of contact under each section, instead of the recommended fender washers behind the individual bolts. If you would like more info on the install please let me know.

Greg,
Can you get into detail about the backing plates and where you put them? I'm looking at the H3O davit, it looks super clean and that's important to me. Structurally, I'm not sure where the backing plates should be to spread the load out. Through bolt or am I missing something from your setup? Thanks!

[kingstonal]

have you ever thought about a electric seawisw davit system.

[Pete]

Source of the post have you ever thought about a electric seawisw davit system.

I just checked the video out, very interesting and clean. I still will need to figure out the through bolts. Thanks for pointing it out.

[kingstonal]

Pete, I own Als marine services in Kingston and we can install if anybody is interested. Also do nautikflor flooring. Check out our Facebook page

[Tireless]

Source of the post

Source of the post

After having my swim platform examined by a fiberglass guy for stability, I installed it myself using a 6 mm poly template I made from the previous boats installation. There is more to this than just drilling holes for bolts and backing plates. I oversized all the holes and filled with epoxy prior to drilling the required holes for bolts. This was done to prevent water intrusion into the balsa core in the swim platform. I also beefed it up by using a two large 1/4" thick marine aluminum plates under the three points of contact under each section, instead of the recommended fender washers behind the individual bolts. If you would like more info on the install please let me know.

Pete;

I looked into the Hurley H30 davit system, as a friend of mine has it. I have a storage box on my swim platform and I did not have enough clearance for my dinghy on that system. I am not sure if you have the storage box, but if you do, make sure you have the clearance or your dinghy will not fit. With the H30, make sure you get the electric winch, as the hand crank does not cut it.

As for the backing plates. My system has three points of contact for each side, so I made a triangular shaped backing plate from 1/4" marine aluminum that put all the bolts through the same backing plate. Using fender washers for my application would not be strong enough IMHO.

As you can see in the pics, the backing plate corresponds to the holes that I intended on drilling through the platform. The davit mounts are on top of the swim platform and the plates are located under the swim platform. You can get access to the underside of the swim platform through the storage area under you cockpit and you will see they are not exposed to the water, as the hull is under that.

For your application you would make a plate larger than your bolt pattern, so all the bolts are going through the same plate. I also put fender washers on the back of the plate so the nylocks would not be torqued into the aluminum backing plate. I drilled the holes in the platform first and then in the aluminum once lined up underneath using a metal bit.

The swim platform has a 1" balsa core sandwiched between two layers of fibreglass. If you do not drill your holes properly you could have water intrusion over time, that will degrade the balsa core. I recommend that once you figure out where your holes will go, drill down through the top layer of fibreglass, into the balsa core, but not through the bottom layer of fibreglass on the underside of the platform. Use an oversized drill bit for this hole. Then take a bent nail, bent 90 degrees about a 1/4" and put it into your drill. Stick the bent nail in the hole you drilled and carefully spin it to clean out the balsa core under the fibreglass around the hole. Once you have a void around each hole, fill the hole with epoxy to the surface of you fibreglass and let it harden. I used the West Marine six ten pre mixed epoxy, as it comes in a caulking gun and easy to use. Once hard, then drill your holes for the bolts to the proper diameter right through the epoxy and the bottom layer of the fibreglass. In my picture above you can see my oversized holes after they have been epoxied. Use masking tape on the topside or you could make a mess of you fibreglass. Also make sure your holes are not outside the perimeter of you top mounted plate.

This should prevent any water intrusion from getting into the balsa core. I also sealed around the hole with 3M 4200. 3M 4200 is not enough on its own to prevent water from getting at the core. Over time it will fail, so thats why I used the epoxy.

If you have any question let me know. I hope this helps you out.

Greg

[Viper]

Source of the post.... take a bent nail, bent 90 degrees about a 1/4" and put it into your drill. Stick the bent nail in the hole you drilled and carefully spin it to clean out the balsa core under the fibreglass around the hole.....

I use an Allen key for this purpose. Cut the short end to about a 1/4" long, that'll give you a 1/4" epoxy barrier around each hole that will serve for both preventing water intrusion into the core and preventing core compression when tightening down the base against the platform. You may also want to consider using butyl tape rather than caulking, it is a superior way to seal IMO. I rarely use caulking now.

[Pete]

Great stuff guys, really appreciate that. I took a closer look today through the hatch, and its tight in there to get a visual, but I understand the concept.

I have a few more issues with the potential install as I looked closer at it. The boat will be out of the water next week getting the bottom painted so I'll look again.

[kingstonal]

i am supprise pete you never heard of seawise davits before, living on the west coast. we i boated out their, all i ever seen was seawise davits