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Old 04-11-2022, 07:28 PM   #1
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Tender

So looking at a 1987 36ft Grand Banks Classic, the boat has a tender on a Seawise davit system, 9.9 4 stroke outboar and a fiberglass bottom with inflatable chambers, proably weighs 230 lbs, I have another tender that has a steering console and would probaby add 120 lbs so total of 350lbs, does anyone else have this setup on the original swimstep ?? , the brackets on Seawise run all the way to just before transom so all rails are incorperated and I believe it has rails on bottom tthat is bolted thru for total capture of swimstep rails
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Old 04-13-2022, 12:38 PM   #2
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I was also wondering if the extra weight on the back of the 36 Grand Banks Classic could affect the trim ??
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Old 04-13-2022, 01:46 PM   #3
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I would not be concerned about the weight as far as the boat is concerned. But the SeaWise davits have a weight limit. Talk to Stuart at SeaWise about it. He was very helpful when we had our SeaWise davits.
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Old 04-13-2022, 03:35 PM   #4
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You may have seen my previous posts about the inadequate swim grids on GB 36 and 42s. IMHO they ought to be more robust by a lot.
I know of one that has recently installed a SeaWise system, the hand crank one, and carries a dinghy similar to what you have described. I will be watching it for failure, as I doubt the swimgrid is strong enough to last with that system attached.

My own dinghy was originally on a SeaWise. I don't know the boat it was on, but when the owner moved boats, to one too long for his owned slip, he sold me the dinghy.
Not clear at the time of purchase was the damage to the dinghy from being supported by the SeaWise stern attachment. That corner of my Caribe 12 weighing in total, including its Honda 40 and a full tank of gas, is over 750#. That was clearly far in excess of the ability of the port, aft corner to handle while bouncing along on its side on the SeaWise.
Yours may be light enough, but you need to know for sure before going to the expense of that davit system.
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Old 04-13-2022, 03:37 PM   #5
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I think your original approximate 230 lbs may be a bit light though. A Mercury 9.9 four stroke is slightly more than 100 lbs by itself. Add a few gallons of gas and youíre at 120 before the boat and auxiliaries. It may be worth a quick second lookÖ. I only believe this as I ran through similar mathÖ.
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Old 04-13-2022, 06:49 PM   #6
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I have an older GB36. It has four supports. IF yours is similar and the seawise is installed on top of one support then I see no problem if the mounting plate spans over the support to the transom to avoid flexing one point.
As for weight I removed a fiberglass dingy hanging on the lip of the swimgrid that needed two strong men to pick up. Guessing 350 lbs without motor. I now have my 180lb dingy incl. motor on top of the aft cabin. I like that setup way better.
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Old 04-13-2022, 07:51 PM   #7
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Quote:
Originally Posted by Soo-Valley View Post
I have an older GB36. It has four supports. IF yours is similar and the seawise is installed on top of one support then I see no problem if the mounting plate spans over the support to the transom to avoid flexing one point.
As for weight I removed a fiberglass dingy hanging on the lip of the swimgrid that needed to strong men to pick up. Guessing 350 lbs without motor. I now have my 180lb dingy incl. motor on top of the aft cabin. I like that setup way better.
I should explain.

My original swimgrid extended 20" back from the transom over 5 bronze supports designed almost identically like those on the GBs. Mine were dimensionally different, to accommodate my slightly larger swimgrid, and there are 5. I had one of those supports fail, without the added stress of a SeaWise system and its added dinghy weight.

My dinghy has never been mounted on the swimgrid, as I have a pair of davits attached to the transom to hold it.

My Swimgird supports were replaced with a set of SS supports properly designed to allow me to increase the depth of the swimgrid by 13" so it is now a useful size, safe and convenient to walk on. If I was going to a SeaWise system, I would probably trust those SS supports to handle the extra load. I know the old bronze supports couldn't do it.

With the failure of my dinghy's own aft, port corner at the SeaWise attachment point, (without doing the engineering) I would expect those same forces to exceed the forces, likely just the weight of people walking on it, that caused one of my swimgrid supports to fail.

Go ahead and use an unmodified GB swimgrid to support a SeaWise with a heavy dinghy, others do, but do so knowing the risks.
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Old 04-13-2022, 08:44 PM   #8
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Keith my old dingy which came with the boat, and with a 5HP motor was attached to these weaver davits (for sale $250)
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As the dingy had a swivel on the transom
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of course I would leave it on. That made it heavy but the swimgrid was unaffected. The weaver davit near the stern of dingy did not like the weight bouncing there. Since I prefer RIB anyway, that issue solved with sale and purchase.
For the purposes of this thread the dingy weight with motor did not make a difference to the swimgrid support which is original.
Of course I have an older boat so maybe newer ones are not as strong.
I remember launching the dingy the first time the wife was standing on the swimgrid asking for assistance getting into dink. I was concerned adding my weight to the grid.
So if it can support two healthy adults, are we over thinking this?
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Old 04-13-2022, 10:17 PM   #9
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Originally Posted by Soo-Valley View Post

So if it can support two healthy adults, are we over thinking this?
OK, I agree that even that swimgrid design is ubiquitous. many examples are undisturbed on up to 50 yr old boats.
I can't forget that I have also seen the swimgrid destruction on those GBs that have erred in backing into (or being run into) some immovable object. Two local examples come to mind. Both shattered when a better design would not. With care, they could last for a very long time, but an errant dock strike is fatal, design being at fault. Too short (by at least 1/2, flimsy wooden construction, inadequate supports. Add weight or stress at your peril. Otherwise I agree no other popular trawler has hit as much of a home run as GB.
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Old 04-13-2022, 11:26 PM   #10
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Just because it can support 2 men at the dock donít mean it can do it in a seaway with the up an down movement of the boat.
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Old 04-14-2022, 10:25 AM   #11
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Totally get where everyone is going, the Sea Wise davit system I have is built to handle the weight of my tender which I estimate around 380 lbs, I pulled it off of my last boat and my use it if the setup on the 36 GB is not of the heavier stuff, as I mentioned the current setup on the 36 GB has a fiberglass bottom 10 ft Caribe with a 9.9 4 stroke so my guess is about 280Lbs and that is with 5 gallons of fuel, my tender from my other boat is an Achilles HB-315LX with the steering console and 15 HP 4 stroke comes out about 380 Lbs s' hopefully if it is held stable and not bouncing or whatnot that the swimstep will accomadate, and I can always be sure to spread the weight distribution out by installing stainless strut under the swimstep to reinforce and tie it more together !
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Ray
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Old 04-14-2022, 02:19 PM   #12
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Quote:
Originally Posted by Rippy45 View Post
Totally get where everyone is going, the Sea Wise davit system I have is built to handle the weight of my tender which I estimate around 380 lbs, I pulled it off of my last boat and my use it if the setup on the 36 GB is not of the heavier stuff, as I mentioned the current setup on the 36 GB has a fiberglass bottom 10 ft Caribe with a 9.9 4 stroke so my guess is about 280Lbs and that is with 5 gallons of fuel, my tender from my other boat is an Achilles HB-315LX with the steering console and 15 HP 4 stroke comes out about 380 Lbs s' hopefully if it is held stable and not bouncing or whatnot that the swimstep will accommodate, and I can always be sure to spread the weight distribution out by installing stainless strut under the swimstep to reinforce and tie it more together !
Thanks
Ray
If I was doing what you are contemplating, I would remove the existing support and replace it with one that is SS and robust enough to handle the extra weight.
Mine are 1/4"x 2" SS flat bar for the vertical and horizontal parts and 1.5" pipe for the support. I don't recall the pipe thickness and it cant be seen to get that measurement. Your welder should be able to advise on that. My 5 supports, all for a 33" deep swimgrid were ~$200 each over 15 years ago. I hope this helps your planning.
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Old 04-14-2022, 02:48 PM   #13
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If I was doing what you are contemplating, I would remove the existing support and replace it with one that is SS and robust enough to handle the extra weight.
Mine are 1/4"x 2" SS flat bar for the vertical and horizontal parts and 1.5" pipe for the support. I don't recall the pipe thickness and it cant be seen to get that measurement. Your welder should be able to advise on that. My 5 supports, all for a 33" deep swimgrid were ~$200 each over 15 years ago. I hope this helps your planning.
It will be more expensive than that now. I just paid $90 each for a 4Ē round 1/4Ē thick 316 S/S with some holes for my swim platform extension. One machine shop wanted $190 each.
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Old 04-14-2022, 03:51 PM   #14
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If I were to replace the support or just add more I would consider using 1 5/8 stainless steel strut, it is veru strong and I am familar with it as I used this a lot as an electrician building support for everything, I can also utilize angle brackets with stainless hard ware, pretty much bullet proof !
I do appreciate all the ideas that you are giving and being a possible GB owner ( will know more after I get the survey report on Tuesday
say how can I put pictures up on my post as I would like to show some of this boat to you !!
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Old 04-14-2022, 04:03 PM   #15
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How can i post pictures please !

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Old 04-14-2022, 04:38 PM   #16
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How can i post pictures please !

Ray
On the home page there is a category of how to use the forum. In it there is a sticky on how to post photos.
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Old 04-14-2022, 09:22 PM   #17
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dinghy on Sea Wise davit

We have a 32 Grand Banks with an Achilles HB 280 DX (148#) and a Tohatsu 9.9 electric start EFI engine (106#) along with a battery and fuel tank, (WAG 40#?) so about 294# total, mounted to the factory swim step with a manual Sea Wise davit. We are very happy with the setup and it works well for us. We have always had the dighy on top of the boat (aft cabin or flybridge) on previous larger boats, while I am not enamored with the appearance of the set up we have now, there is no other option. And, it is MUCH faster and easier to deploy.
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Old 04-14-2022, 11:05 PM   #18
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We loved our SeaWise davits that we put on a previous boat. Really fast and easy.
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Old 04-14-2022, 11:43 PM   #19
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so I am still trying to upload pictures so bear with me, your set up look like the one on the 36 that we maybe buying and I would just swap my own tender for that one as I have a bench seat and steering console so add about an extra 100 lbs for that so would be 400 lbs Click image for larger version

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Old 04-15-2022, 10:45 AM   #20
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Hi, so sometimes I get the attachment paper clip and sometimes not , I will just have to play with it, going for the survey this Monday and getting pretty excited, seems in my mind I am only doing the survey stuff for insurance etc, but I still need to know as I do know better than to buy without a decent surveyClick image for larger version

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If this all goes as I expect I will put a profile picture in with the 36 GB
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