Arch Davit System for 38cc-Can your dinghy be too big?

FortAwesomeIII · #1 (**permalink**) 12-28-2007

Hello-I'm having an arch davit system built for my Endeavour 38cc similar to the type that WellsMarine offers(but hopefully a lot cheaper). I just purchased a Zodiac Yachtline Deluxe RIB with 30hp 4stroke Yamaha I would like to suspend from said arch. Currently, I have a Mercury 340 Ocean Runner RIB with 15hp 4 stroke yamaha outboard hung from small davits. With gas, the whole thing probably weighs about 300lbs and is quite a chore to raise with the 3:1 hand winch system I am using.
So, I am fishing for recommendations for a davit system. Would yall opt for a rope and triple block purchase system or higher powered hand winches? Or something else? The new tender weighs in about 700lbs fully loaded. The arch will be built from 1.5" stainless steel tubing.

By the way...the boat is on a lake and will not have a chance of being overcome by following seas.

Thanks for the help!

Freesail99 · #2 (**permalink**) 12-28-2007

I am not sure I follow. If your having an arch davit built, why are you looking for recommendations for a davit ? Or do you mean a pulley system ? If your on a lake, why the need for an arch ? I had a davit built by Garhauer marine and they added an additional cross support so I could mount solar panels. I may even have room on my stern rail for a BBQ.

If it is a pulley system your looking for, I suggest taking a few pictures of a davit on another boat and copy it.

FortAwesomeIII · #3 (**permalink**) 12-28-2007

Quote:

Originally Posted by Freesail99

I am not sure I follow. If your having an arch davit built, why are you looking for recommendations for a davit ? Or do you mean a pulley system ? If your on a lake, why the need for an arch ? I had a davit built by Garhauer marine and they added an additional cross support so I could mount solar panels. I may even have room on my stern rail for a BBQ.

If it is a pulley system your looking for, I suggest taking a few pictures of a davit on another boat and copy it.

Good question...I am having the ARCH itself built by a qualified stainless steel welder, but not a marine welding company. Hence the savings. Looks like I can get this done for about $2500. I'd like to add in a possible mount for future solar panels(no need for lake cruising), 2 stern anchor holders and maybe 2 spools of rode, a kayak storage rack on top and forward, speaker and light mounts, and of course the davits.

The structure for the arch will be made for me-I am responsible for designing and installing the process for raising the tender.

Freesail99 · #4 (**permalink**) 12-28-2007

Another thought I had, with over 300 pounds in your motor and Zodiac, do you really want to add another 100 plus pounds to the rear of your boat with the arch plus the weight of a davit ? It will affect how your boat sails.

Sasha_V · #5 (**permalink**) 12-28-2007

You can also hang two motorcycles and a small SUV off that rack so you have shore transport when at the dock!

Jeff_H · #6 (**permalink**) 12-28-2007

Yes, you can have too heavy a dinghy for a 38 footer. 700 lbs is is an absurdly heavy dinghy for a 38 footer especially when you consider the weight of the davit and everything else that you are planning to add to it. You're joking...Right?

That kind of weight will alter the way the boat sits on its lines sufficiently that it will alter the balance and handling of the boat. (Visualize sailing around with 4-5 crew members hanging off the transom.) That kind of trim change can result in lee helm and other dangerous handling characteristics such as forcing the cockpit drain and exhaust under water.

Beyond the sailing and trim issues, you have some big structural problems. You will need to beef up the hull and deck at the mounting points, make sure you have stiff enough and large enough bearing plates to distribute the loads without crushing the deck, and then distributing these loads through the hull.

As for the lifts, you are looking at lifting 350-450 lbs on each (engine side supporting more than the bow). Normally the purchase on control lines are designed to have a max load on the fall of about 30 to 35 lb. That would require a purchase of something like a 10:1 to 14:1 purchase. That's really not practical, so I think you are looking at winches and cable, and with that kind of load, unless you want to end up with Popeye style forearms, I would think that electric winches make sense.

Respectfully,
Jeff

Freesail99 · #7 (**permalink**) 12-28-2007

If your on a lake, it make make more sense to just tow the Zodiac.

7Psych · #8 (**permalink**) 12-28-2007

Quote:

Originally Posted by Jeff_H

Yes, you can have too heavy a dinghy for a 38 footer. 700 lbs is is an absurdly heavy dinghy for a 38 footer especially when you consider the weight of the davit and everything else that you are planning to add to it. You're joking...Right?

What he said!

FortAwesomeIII · #9 (**permalink**) 12-28-2007

Thanks for the opinions everyone...I do still plan to go through with the project and hope that it doesn't affect the boat as drastically as you're saying.

I like the comment about the SUVs and motorcycles-that's so true! You are dealing with someone who will load a three wheeler into a zodiac so I can take it to the islands to ride or the other side of the lake!

The weight issue-I have added about 350-400lbs of chain in the bow along with a coming windlass and battery in the bow, which will add some weight. I know it is best not to add weight on the ends, but this should help balance it out a little bit. The Endeavour is not a light boat. Mine should weigh in currently at over 20,000lbs. I'm also thinking of adding a separate battery bank of 2 4d batteries in the forward part of the boat, maybe under the Vberth.

As far as towing the boat, I will probably be towing a Sea Doo or something else, so I prefer to have my dinghy on the boat. I am a toy fanatic, and prefer to have as many options as possible when out. The dinghy I purchased is great because i can get back to the dock quick to grab something or pick somebody up.

I know I'm a little different from most of you in your "style" of cruising and outfitting your vessel, but I value any opinion and appreciate your info!

sailingdog · #10 (**permalink**) 12-28-2007

Almost 800 lbs. at the very stern of your boat... hmm... not exactly a good idea IMHO. Adding solar panels and such to the davits is going to make your boat very tail heavy and have some serious performance consequences.