Weight limit on aft cabin top for dinghy

[GrandWood]

Looking to store a dinghy on a GB36 aft cabin top, and can’t seem to find a weight limit for the cabin top. What length dinghy do you guys recommend as well. Does not look like there’s a lot of room.

Also how much would the boom and mast be rated to lift. Thinking of a pole Davit over using the boom.

Just asking for future reference, thanks

[SteveK]

My hard bottom 270 plus 5hp OB weighed just under 200 lbs. Sat on cabin top and used the boom to launch and retrieve. No idea what a max may be.

[jwag956]

Our 1989 42C has a 450# dinghy + motor...
As for mast/boom - posts I've read here mostly say - 'don't do it' unless very light. Also - from looking at lots of pictures and GBs in the harbor there are many many mast/boom configurations (hinged at bottom, in the middle, different heights, etc.). We have a Nick Jackson #500 davit (which BTW isn't really enough for the 450# dinghy).

[SteveK]

Originally Posted by jwag956

Our 1989 42C has a 450# dinghy + motor...
As for mast/boom - posts I've read here mostly say - 'don't do it' unless very light. Also - from looking at lots of pictures and GBs in the harbor there are many many mast/boom configurations (hinged at bottom, in the middle, different heights, etc.). We have a Nick Jackson #500 davit (which BTW isn't really enough for the 450# dinghy).

This is one of those TF comments that advise without substance. WHY? Have you had a mast and boom failure?

[Comodave]

My concern wouldn’t be the cabin top for weight but can the mast and boom handle that weight.

[koliver]

There are many different masts and booms on GB 36 and 42s. You need to know what is the capacity of your particular equipment. You need to know the weight of your dinghy.
36 has a different length available for dinghy storage than does 42. You need to know that. Your dinghy will sit on the best space available for your BBQ and the associated accoutrements. Those will be lost by putting a dinghy on that surface.
When you have all of those variables figured out, ask your remaining questions, if any.

[GrandWood]

Originally Posted by koliver

There are many different masts and booms on GB 36 and 42s. You need to know what is the capacity of your particular equipment. You need to know the weight of your dinghy.
36 has a different length available for dinghy storage than does 42. You need to know that. Your dinghy will sit on the best space available for your BBQ and the associated accoutrements. Those will be lost by putting a dinghy on that surface.
When you have all of those variables figured out, ask your remaining questions, if any.

As per SteveK above (his GB36) boat I’m interested in, does at least 200lbs. Just wondering if anyone had specs on the weight the cabin top will hold. His dink that he had on there I think was 8ft long. Thinking 10ft would be too long to mount safely either way.

Jwag who responded has 450lbs plus the weight of the OB on a 42, thinking the span is less on the 36, so maybe that’s a safe weight and that I would be comfortable with.

BBQ will go on the side railing, Port or starboard side is my preference.

I can’t find any dimensions or weight load of the entire cabin top on a GB36, hence the questions.

[GrandWood]

Originally Posted by SteveK

My hard bottom 270 plus 5hp OB weighed just under 200 lbs. Sat on cabin top and used the boom to launch and retrieve. No idea what a max may be.

Sounds good Steve, just been looking around for a dinghy that would work on the cabin top and seems a 8ft with 6hp will be no problem. Most I see on GBs are 10ft mounted on swim deck, just I’d rather it up behind the house, then hanging off the swim deck. That’s just my preference not based on anything other than that.

Also why even bother keeping the boom if not to lift a dinghy, haven’t seen to many that still have the sail with the boat, and from what I’ve read, the sail doesn’t help that much with roll.

[SteveK]

The length is a limiter for hanging off over deck.
Mine will have ob agai st back cabin wall.
Consider the roof over stateroom holds same as the bridge. Then if 4 adults are no issue up there, 4 adults weight on stateroom should also work. But I would not be lifting more than 300 lbs as it is the guy wires mounting location that counters the end of pole load.

[CharlieO.]

I have a 34' Marine Trader. I plan on using the mast and boom to hoist the dingy. I am reworking all my cable stay holds and mounts to be sure I can trust them.

I plan on storing the dingy on my aft cabin roof, but plan on raising my dingy cradle\saddle up a little so the bow of my dingy will overhang just a bit onto the fly bridge deck just to minimize the over hang over the aft deck and allow me to look out the port aft window under the dingy. I will store the outboard inside the dingy.

At least that is how I envision it in my mind.

[Choices]

The number on the old GB forum was 350#.

The problem is the guide wires pulling from the deck or railing.

350 on the end of the boom is a lot of leverage. My rig was about 200# and never had a problem, and I have to lift higher than you.

[Benthic2]

How substantial are your dinghy requirements. A fabric bottom dinghy with inserts and removable motor makes almost anything possible. Add a low cost compressor so you can deflate a section or two and you could store it anywhere. You just have to decide whether to prioritize dinghy capability or deck space.

[Cigatoo]

The house is structurally sound. Has fiberglass ribs every 18 inches or so. Is the least of your worries. I would certainly beef up the shrouds where they attach to the flybridge. (Forward shrouds) if you are going to lift with the boom. However it’s no picnic hauling the dingy using the boom. We have a Trinka up there now. We use it for storage and it looks pretty but it doesn’t move from the top of the house. We tow the inflatable. Outboard and all.

[GrandWood]

Originally Posted by Benthic2

How substantial are your dinghy requirements. A fabric bottom dinghy with inserts and removable motor makes almost anything possible. Add a low cost compressor so you can deflate a section or two and you could store it anywhere. You just have to decide whether to prioritize dinghy capability or deck space.

I’d like a hard bottom dinghy, will be used to go to shore, set traps, take dog to shore a few times a day, explore along inlets and such, will basically be my car. Plan is to live on the hook, summer along the BC coast staying in inlets, visiting small remote towns, hit a dock/marina when I need a pump out, fuel, or a few provisions.

As I gain experience, would like to make a trip to Alaska, and maybe even as far as Mexico. Plenty to explore from Seattle to southern tip of Alaska to last me for sometime, winter in SanFrancisco Bay Area or Fort Bragg, Noyo inlet.

So I feel a dinghy is an important piece of equipment for what I’m looking to do.

I’m not buying a boat for weekend/weeklong trips, I’ve sold my home, currently trying to get rid of cars, motorcycle, snowmachines and gobs of household stuff and accumulated junk to liveaboard for the rest of my days.

Woohoo!!!!

[Pete Meisinger]

I think your aft cabin can easily hold 500 or more pounds. The problem begins when you have the dinghy sitting there and then two or three people congregate there also. Plus what might be in the dinghy? it is the add ons which will eventually break the back.

pete

[Bongi]

Hope our dear GrandWood got an answer that helped. We have a GB 42 and I think we may have pushed some of the limits in this area which would help him know the boundaries.

We have a semi-ridged AB 10ft with a 30hp Tohatsu totalling 520lbs. We haul that effortlessly with the excellent engineered 700lb Nick Jackson Davit which they make standard for a GB. The limit is not the cabin top strength as noted, the limit for us is the space in the beam where the tube compresses against the mast receptacle pole. The other side encroaches a little into the side deck walkway. The outboard hangs over the cabin top a bit, but in the vertical position it only impedes opening of the one lazarette hatch lid.

After 20,000 miles of cruising (on a 30 ft sailboat) we’ve learnt that your dinghy is a vital transport for all sorts of things, especially when in distant and rural ports, e.g. getting propane refilled. Hope this puts the limits in perspective and helps you extrapolate for your needs.

This picture shows the arrangement, though on this day we had not yet figured out a slightly deflated tube allows us to get the outboard real close in!

[Steve1.0]

Bongi, could you (or anyone with same) post a pic or two of the upper and lower mounting of the NJ pipe davit please.

[Bongi]

Here you go… the key thing to note (and needed a paradigm shift for me) is that the pipe does not penetrate through the deck. Instead, the Davit is supported by :

1. The bolting through of a mount plate underneath the lip of the bridge deck

2. A circular base plate with a ring lip which gets bolted onto the roof of the cabin. The pipe then fits snugly over that ring shaped lip on the base mount.

These two mount points gives it a sturdy two point mounting, which gives it it’s strength.

Hope this rambling answer helps clarify.

[Steve1.0]

Originally Posted by Bongi

Here you go… the key thing to note (and needed a paradigm shift for me) is that the pipe does not penetrate through the deck. Instead, the Davit is supported by :

1. The bolting through of a mount plate underneath the lip of the bridge deck

2. A circular base plate with a ring lip which gets bolted onto the roof of the cabin. The pipe then fits snugly over that ring shaped lip on the base mount.

These two mount points gives it a sturdy two point mounting, which gives it it’s strength.

Hope this rambling answer helps clarify.

Thanks, perfect! I'm welding a davit myself and am looking at different methods of mounting. Pics to follow.