Arch? Davits? Wind Vane ?

[Tspringer]

Hmmmmm On a live aboard blue water cruising boat it would sure seem that having an Arch that also functioned as davits for the dinghy would be a sweet setup, particularly on a center cockpit boat.

The Arch gives a perfect place for solar panels, wind generator, radar and a means of building in davits so you can haul the dinghy up at night for safety.

A wind vane for efficient self steering on passage is also on my list of what I want on a cruising boat.

But can you have both?

It would seem that all the gear stuck on the back of the boat for the windvane would make using davits for the dinghy impossible. Or do folks remove most of the windvane parts and only install again for a longer passage? Any ideas? Both or either/or ?


Terry

[RaptorDance]

We have an arch and Monitor Windvane. Would recommend both if your boat can carry that much weight (from the arch) aft.

We mounted our solar panels above our Bimini - see
Raptor Dance - Solar Panel Installation

In our opinion - Davits don't belong on a blue water boat. Too much danger of losing your dingy, davits, large chunks of your stern, etc. from a large following sea.

[AnchorageGuy]

On the other side, we have carried our dinghy on davits and cruised extensively for 16 years. We have carried the dinghy on every offshore passage and it has virtually survived full gale conditions with 55 sustained winds and seas that were breaking over the cabin top. No damage to the dink, boat or davits, but that is just our experience. we have wrestle with the wind vane issue also and finally gave in to a below decks autopilot (WH Autopilots) and have been very happy with the combination. We do consider Sea Trek a "blue water" boat but again that is just our opinion and everyone is entitled to there own. Not everyone has a large enough boat to carry a dinghy on deck so compromises are a fact of life when cruising. I don't believe towing a dinghy is an option for offshore passages but sometimes it is done successfully. Depending on the boat and the set up I suppose some type of combination is possible. Here is our set up IMG_1667.JPG (image)
of course it is strapped down securely while under way.

[Sailabel]

Terry- our arch/davits are almost complete, and should be installed by Wednesday. Our boat is a 'double ender' and has very limited storage at the stern. We had put together mounts for the wind generator, radar, solar panels, outboard motor, antennas, etc., and found that it really didn't work for us. We also have an wind vane">Aries wind vane. Our arch is designed to have high davits that will hold our RIB dinghy when at anchor or calm sailing conditions. Offshore, we plan to continue to carry the dinghy on the foredeck/cabin top. The davits rotate, so they swing inwards when not in use; and are high enough for the dinghy to clear the wind vane mount. Offshore, we use the wind vane- so keeping the dinghy on davits is not an option anyway.

It looks like the whole set-up will add 150# to the stern... not including the dinghy.

Our goal was to brace up the stern to securely carry the "stuff" lashed back there, as well as have another way to raise the dinghy each evening (we currently use the spinnaker halyard). We are keeping our solar panels lower, due to the limited size of our arch and the desire to keep windage down.

Steve

[Steve Pope]

I have davits on a boat that is over 30 years old, there are many overseas yachts that come down to NZ that have davits. Re selfd steering it depends on the type of rudder setup you have. Fitting an Auto-Helm auxilliary rudder (Scanmar marine) and wind vane can / will allow you to have your davits and vane at the same time. You install the vane assy on the arch and use longer cables to operate the trim tab, its as simple as that. Or if your boat already has a trim tab as mine has you only need to purchase the upper unit. Those I have spoken to who have the Auto-Helm seem happy with them and a solution to your problem.

[Tspringer]

Thanks for the replies... lots of good ideas.

A boat I am giving thought to has a monitor windvane installed. One of the things I would add would be an arch, probably go with a Wells Arch with davits provided that the davits can be done so they rotate out far enough to ensure that the raised dinghy does clear the windvane.

I would only plan to use the davits to hold the dinghy when day sailing or perhaps on overnight passages. Anything longer than that and it would go on deck. Another big use for the davits to me would simply be as a very easy way of raising the dinghy up at night for theft prevention.

I had not thought about having the davits attach to the arch and be able to wing out further so they could clear the windvane apparatus. That would seem to offer a solution.



Terry

[Steve Pope]

My davits are part of the arch, a better way that I have seen is to bend a tube (40 to 50 mm dia) in a wide U shape to match the arch shape but also to match up with the pick up points of your dinghy, the dinghy is attached using short strops (dyneema maybe) and the whole assembly is raised by a single multi purchase block setup, the ratio to suit the weight of the dinghy and the strength of the user. The lifting frame can incorporate brackets etc to allow the dinght to be ridgidly attached for long passages.
Re self steering you can attach a small tiller pilot to the monitor and detach the vane altogether this uses minimal power and is especially useful in light airs. see <http://www.svsarah.com/Whoosh/Boat%20Mods.htm>as to how they have done this

[Rangiroo]

Terry you just need to bite the bullet and come down to Savannah one day and look at our boat...you'd have a MUCH better idea in your mind after seeing what we did with the arch etc....open invitation.....

[Benjamaphone]

Bended steel davits will want to keep bending while under load, which presents some clear dangers. They may be more expensive, but cast, or modular davits are far more valuable for the money.

Its also important to keep the lifting ratio in mind, a dinghy hanging from your transom in rough seas, half filled with water and fuel can make for a difficult situation. Make sure you have at least a 6:1 lifting ratio for anything more than 100 lbs.

Another important point is that any davit system you make/buy should have a very wide margin for safe working loads. Davits may be tested on the hard without taking into account the extreme lateral forces experienced by a bucking vessel in choppy water.

When you're out on the water the last thing you want to have to worry about is your dinghy breaking loose. Many of us enjoy sunday afternoon sailing but it is still important to plan for those other days.

[Sailabel]

I just learned another lesson about davits this past week, just after having them installed as part of our arch. Benjamaphone is correct, in that just having "bent tube" davits can create an issue when loads are applied at sea. We just had our "bent tube" davits reinforced with a "ladder" type truss, as well as an insert into the tube to reinforce the contact points. A cross brace was also installed. At the dock, the "bent tube" was fine for just lifting the dinghy, but add an outboard motor... it was a bit too much. We won't sail with the motor attached, but want to raise the dinghy/motor while at anchor.

We have a rather heavy RIB- a Walker Bay Genesis with a 15hp outboard... so the davits need to reasonably hold 250-300 pounds. Not too tough, but underway, the dinghy itself will add tremenous forces (something like mass times acceleration???)

We're OK with a 4 to 1 lifting system. We made sure that we had a fair lead and enough line to use our primary winches for assistance if needed. But so far, the 4 to 1 is fine for us. A bit of a pull, but a lot less line to mess with.

Ours is now set up that we can use the davits with the paddle removed from the windvane, but we have to push the dinghy around the mount assembly. For now, I've just removed the whole windvane for the daysails. When we make a longer passage, the dinghy will go back on deck, and the windvane will be reassembled.

Steve

[Benjamaphone]

For situations such as yours, where a lot of weight is being held and you require a lot reach we have a solution. With that kind of weight the loads under sail are such that only a cast davit can be completely trusted. Other than far greater strength than SS tube davits, the model 2000 is modular with the added advantage of an optional extended 26" riser arm. If that reach still is not enough to clear any other hardware, it is possible put two 18" risers together provided that the proper extra supports are added. This means that we can mount your tender far enough away from your windvane paddle so that both can be used.

As for the lifting ratio, this particular model is fitted with a 7:1 purchase and is available with an optional winch. At 300 lbs. we believe that the davits should be doing most of the work, not the sailor.