FAQ's
What do your part numbers mean?
Why would I use a rail mounted davit?
Is my boat's rail strong enough?
How are davits rated?
What stainless is best?
Are all welds equally good?
What polishing processes are used?
Why would I want a rotating davit?
How do your davits rotate?
Can I leave the dinghy free to swing if I wish?
What prevents your davit system from swinging?
Can I fold your davits in easily?
Can I use one davit to lift my outboard motor?
Why does a davit have the reach that it does?
My yacht has a transom with a reverse sheer, do I need a davit with a longer reach?
Why does the HSD series davit have an adjustable reach?
Why do you build the davits in two heights?
The MD10 and the MD 20 motor davits seem to be identical - what is the difference between them?
When would I want a tackle ratio greater than 4:1?
What makes your outboard motor sling better?
Is it best to let the dinghy swing free, or tie it in place?
How can I prevent my dinghy from swinging?
How much closer than the distance between the dinghy's bow and stern should the outer ends of the davits be?
What are ratchet straps used for and why are they better than rope?
I have a hard dinghy. How can I tie this against the davit arm?
Why would I want to install a second connecting strut?
What are cam cleats and why would I want them?
Can I take my boat offshore with the dinghy on davits?
Can I order directly from Ocean Marine?
I have a really unusual problem and I know what I would need to fix it, but I can't find it anywhere. What can I do?
If I am sailing a 3/4 hermaphrodite rigged schooner on a semi-reciprocal bearing, does it matter if I luff or jibe?
What do your part numbers mean?
Our system works like this: 'S' stands for sail (rail mount) davit, 'T' stands for trawler (transom mount) davit, and 'M' denotes "motor davit." 30, 40 and so on represents height in inches to the apex of the davit curve. 'H' stands for "heavy duty." Therefore, an HSD30 is a heavy duty sail (rail mount) davit that stands approx. 30" tall from the base to the apex of the davit curve. This would allow installation on a yacht with a rail height up to approximately 27 1/2". Exception: the motor davit number represents lifting capacity in pounds, actually standing 60" tall. The HTD40 trawler davit is actually 45" in height.
Why would I use a rail mounted davit?
By rail mounting, we have a system that requires minimum custom work to install. With so many yachts on the water, there is far more commonality in the rails than in the yacht designs. Therefore, it is possible to offer a rail mount davit at a much more competitive price and a system that is much easier to install
Is my rail strong enough?
Usually, but not always, particularly if you are planning on lifting a heavy dinghy (over 200 lbs) Also, if the yacht has a split stern rail, there may be too much flex. It is usually a comparatively simple and inexpensive matter to reinforce your existing rail. Please contact us if you think you may need additional supports.
How are davits rated?
Davits can be rated either on the basis of "per davit arm", or on their ability to carry a "safe working load." While both ways are good, we prefer to use "safe working load," as we feel that a per davit arm rating can be misleading. For example,it is quite unreasonable to suggest that a davit rated at 350lbs per davit arm could carry a system load of 700lbs. Our davits have a very large margin of strength designed into them and simply do not fail if used within their designed ratings. However, allowing the dinghy to fill with either rain water or sea water will create a bad day for everybody.
What stainless is best?
Stainless steel is an alloy of iron, nickel and chromium. It is produced in a wide range of metal ratios, but in our industry the most common types are type 304 and type 316. The numbers represent the content of chrome and nickel expressed as a percentage.
The first number is the percentage for chrome, while the second is for nickel. Most yacht rails are made from type 304 stainless tubing - while type 316 is generally engineered more for use below the waterline. Type 316 is more corrosion resistant than 304, but it also more expensive to buy and to polish, because of the higher nickel percentage.
It is important to remember that stainless is stain "less," not stain "free." Type 316 is considered to be better quality than type 304, but all stainless will rust and/or be subject to pitting corrosion, particularly in the presence of brackish water (low oxygen content). The simple expedient of a fresh water rinse and an occasional coat of wax from season to season will keep type 304 bright and shiny as new. 1" diameter is industry standard for most yachts in the 25' to 50' range, while a few yacht builders employ rail structures made with stronger 1-1/4" tubing.
Tubing is available in .049", .065" and .083" wall thickness. Wall thickness plays a role in strength, but also in weight. This can cause a loss in sailing performance for many small yachts when placed in the stern. Similar strength ratios can be achieved with correct design and engineering, and with careful attention to quality control in the machine and in the welding processes used in production.
Are all welds equally good?
Generally, the best stainless welds are produced using a "TIG" process. This means "Tungsten In Gas." The process relies on precision fit of the parts. The best and strongest welds are "tiny," with little or no filler rod required. Stainless needs to be welded at a relatively cold temperature, otherwise the chromium will be burnt from the metal.
A "hot weld" will rust and ultimately fail due to absence of chrome and previously mentioned pitting corrosion. To prevent embrittlement and burning of the inside of the tube during the welding process, the tube should be purged with Argon gas. This prevents oxygen from coming into contact with the stainless until after it has cooled. To prevent "hot" welds and burnt metal, the process must be done quickly. Therefore, it takes many hours of practice to produce a competent welder.
What polishing processes are used?
Electropolishing has long been the preferred process for the bright finishing of stainless steel. This is a process similar to the way in which metal is chrome plated, but is actually the reverse. It is done in a solution tank that is heated. An electric current is passed through the stainless and the solution, causing the removal of a small, almost undetectable layer of metal.
This process is becoming increasingly more costly due to the chemicals involved and certain environmental concerns. Other processes such as "pickling" in certain solutions and hand buffing are also popular. Hand buffing is a trade in itself as producing a lustrous, brilliant finish carries with it many closely guarded "trade secrets." Buffing is however, the most environmentally friendly process. At Ocean Marine we use a combination of these processes.
How do your davits rotate?
Ocean Marine's davits have a bearing built into the bottom of the davit that allows for full 360 degree rotation. Various base mounts can be installed that also swivel. This means that the davit base may be mounted on a surface of any angle. However, in practice, the davit's ability to rotate is limited by contact with the yacht's rail. Our Motor davit, however, will rotate a full 360 degrees.
Can I leave the dinghy free to swing if I wish?
When a dinghy is allowed to swing free, damage is almost certain to result. The constant slamming will cause chafe on the tackles, wear and tear on the davit parts, but most of all rapid and serious damage to the dinghy. Our position is that the dinghy must be tied up securely in such a way so as to prevent any movement whatsoever.
What prevents your davit system from swinging?
Ocean Marine's davit systems include a basic lateral stability system in its standard kit packages. This includes a locking strut kit for each davit. We also offer several different connecting strut options. Reasons for additional and different strut options include provision for rougher water cruising and carrying heavier dinghies that create higher inertial loads. Also, with an extra strut, solar panels may be mounted between the davits or electronics may be mounted in the same location.
Why does the davit have the reach that it does?
The SD series has a reach that is equal to 1/2 of a typical inflatable's beam. This allows the dinghy to be brought up and stored level and still tied up snugly in the "armpit" of the davit. This will aid in minimizing uncontrolled motion of the dinghy when at sea.
My yacht has a transom with a reverse sheer, do I need a davit with a longer reach?
While the dinghy may rub slightly, this will only occur when the dinghy is down close to the water. By gently fending off, this generally does not cause a problem. It is far more preferable to be able to carry the dinghy in the correct attitude when on the davits. Thus a little compromise in favor of safety at sea is suggested.
Why does the HSD series davit have an adjustable reach?
The HSD series is designed with an adjustable reach so that it can be installed on yachts with central back stays, canoe stern yachts and yachts where the davits must be mounted a great distance apart from each other. However, the weight rating is reduced when the davit goes out to maximum reach, due to an increased leverage moment on the davit system.
The MD10 and the MD 20 motor davits seem to be identical - what is the difference between them?
Yes, they appear to be similar, but the MD20 is built from tubing with a wall thickness of .120" - almost double the thickness used in the MD10 and effectively almost triple the strength of the MD10. Also, the MD20 is built with a 6:1 tackle, while the MD10 is built with 4:1.
When would I want a tackle ratio greater than 4:1?
We make our tackles from 3/8" yacht braid, as it is easier to grasp than smaller cordage. It is best to keep the pull on the line down to about 25lbs. If you have a heavier dinghy or an outboard generally larger than about 8HP, a 6:1 tackle makes easy work when lifting the stern of the dinghy. It is seldom required for lifting the bow. It is quite common to have both a 4:1 and a 6:1 on a single installation.
What makes your outboard motor sling better?
Our motor sling is made from heavy-duty webbing rated at 1400 lbs. All fittings and fasteners are made from stainless steel - no plastic to fatigue from ultraviolet radiation. The sling itself wraps around the motor twice before terminating on buckles at the after end of the motor. Even the new design four-stroke outboards cannot slip out of this sling since it continues to get tighter as the motor tries to slide. We think so highly of it that it comes with our unconditional lifetime warranty.
Is it best to let the dinghy swing free, or tie it in place?
Whenever we see a dinghy that has been damaged while carried on davits, it is almost always because the dinghy got loose! Instantaneous shock loads can rise to staggering levels when the dinghy is swinging free. Damage is certain to result. All of the features built into our designs are meant to make it easier to secure your dinghy and to prevent unwanted motion.
How can I prevent my dinghy from swinging?
The ideal position for the dinghy at sea on davits is to have the dinghy as high as possible, sitting level and with the tube of the dinghy tied firmly into the "armpit" of the davit. There are several very effective ways in which to minimize dinghy motion. All of them should be employed at once. First and foremost, the lifting points in the dinghy should be low - as close to the floor as possible. If the slings are not down low then you cannot lift the dinghy up high. Secondly, it is important to adjust the davits so that the outer ends are positioned closer together than the distance between the bow and stern lifts in the dinghy.
How much closer than the distance between the dinghy's bow and stern should the outer end of the davits be?
This varies with each installation but generally about 4" - 6". This is part of the setup procedure and is easily done when the dinghy is first hoisted into position.
All Ocean davit systems include a single connecting strut in the kit designed to achieve this purpose. It is the function of this strut to pull the davits together. As the dinghy is lifted, the tackles should gradually angle in at the top as viewed from the yacht looking aft. The last part of the lift should be a little difficult, since you are effectively trying to "shrink" the dinghy. The engineering term for this is "pre loading". Finally, the dinghy should be tied securely - but not from the rubber tubes. At the stern, a line should be lead from an eye located on the outside of the transom and led back to the yacht's rail or to the cleat located on the davit for that purpose.
With a RIB, a line should be led from the bow towing eye back to the davit or to the yacht's rail. A soft floor, hard floor or inflatable floor dinghy should have a line tossed around the outside of the dinghy, and pulled back into the yacht's rail.
What are ratchet straps used for and why are they better than rope?
We prefer to see ratchet straps used in place of rope for securing the dinghy. Yacht braid tends to stretch when under shock load, causing the dinghy to move at sea when it was snug at the dock. Also, a dinghy sitting in warm water would have its chamber air pressure reduce when exposed to wind chill at sea. Our ratchet straps are made from 1" industrial webbing and fitted with all stainless mechanisms - they also come with a lifetime warranty. If the dinghy is loose at sea, a simple pull on the ratchet strap lever will pull the dinghy back in snug. Security and a feeling of safety is what it is all about.
I have a hard dinghy. How can I tie this against the davit arm?
A trip to the Hardware store is in order here. Get some foam water pipe insulation - the type that is "split" and designed to wrap around 1" and/or 1-1/4" OD pipe. Install that where the dinghy will come in contact with the davit arm, and cover that with clear plastic hose. Secure this into place with a couple of plastic harness ties and you are in business!
Why would I want to install a second connecting strut?
Aside from adding more rigidity to the system, a second connecting strut can be installed parallel to the first, creating an ideal platform for the installation of solar panels. Another way to add exceptional rigidity is to install a pair of connecting struts in "criss-cross" fashion at the outer ends of the davits. This creates triangles, ensuring a system that is totally rigid as the triangle is the strongest structural shape. We also offer a strut we refer to as a 'CS4'. This consists of two struts separated by two welded stainless plates. There are sliding tubes at all four corners that allow overall length to be easily adjusted. Once installed, this adds the same rigidity as a criss cross strut installation, but also allows antennas, stern lights and other items to be installed.
What are cam cleats and why would I want them?
Cam cleats are spring loaded eccentric rope jammers. We install these along with rope fairleads on the small tube midway out on the davit's arm. We machine a custom saddle from white UHMW plastic and install the cam cleats and fairleads on top of it. They are through bolted and secured with "barrel nuts", that hide the threads inside the davit tube - a really nice looking installation. The kit is factory installed and includes installation on both davits. Our davits already have two welded stainless cleats on each davit, but the cam cleats are a real treat to use. You tend to pull the dinghy up "incrementally", and having cam cleats means that you do not have to tie off the line after each pull. Also, the fairleads allow you to lower the dinghy from a central location, or stand down on the swim ladder to fend the dinghy off at the same time as you lower it. Making life easy it what this is all about.
Can I take my boat offshore with the dinghy on davits?
The use of davits is subjective. We all know best the type of seas we are most comfortable or experienced enough to sail in. Our position is this: in your cruising grounds carry anything you like on the davits, up to the designed weight rating of your davit system. If you are making a passage and expect rougher conditions, consider removing the outboard motor. If you are venturing offshore, the dinghy should be lashed on deck - you cannot know what conditions you might encounter and mid-ocean is no place to discover that you should have removed the dinghy.
Can I order directly from Ocean Marine?
Yes, you can order directly from Ocean Marine. Davits are a highly specialized business. While we do sell our products through dealers, they are generally riggers, yards and new boat dealers. Regardless of where you purchase them, we do want to have some involvement with you, the customer. This is to ensure whoever uses the system clearly understand the procedures that need to be carried out in order to prevent problems. We do not sell through marine chandlers as they seldom have staff with the required expertise.
I have a really unusual problem and I know what I would need to fix it, but I can't find it anywhere. What can I do?
You can talk to us. We make products that fulfill mariner's needs. If you know what you need, we may well be able to custom design and manufacture it for you to your specifications. If you "sorta" know what you need, we can work together and come up with the solution to your problem. Unfortunately, "custom solutions to "custom problems" generally come attached to "custom prices".