Intro: Arbor Boat Lift
Boat Lifts or Davits are any device that aids in lifting a boat in and out of the water. Unfortunately by their nature they tend to be rather utilitarian and bulky looking and are not always very aesthetic to have sitting on your deck or dock. Add to this that they are usually made of metal and can rust quickly if not cared for constantly, they sometimes look like giant rusted claws placed on the ends of piers.
Arbors on the other hand are beautiful to look at and are often added to a garden or deck simply to give definition or structure to a space. Since they are generally made of cedar they are very durable for outdoors and do well next to lakes or salt water.
But what if it were possible to combine the utilitarian practicality of a boat davit with the simple beauty of a garden arbor?
We developed the idea of a Arbor Boat Lift/Davit after seeing several historical boat lifts and generally being inspired by garden arbors in our area. This lift won't handle large or heavy boats and it is not designed to hold the weight of people in boats, however it has been a great aid in getting small craft like sea kayaks in and out of the water at various tides and maybe more importantly it looks like a nice and unassuming garden arbor when not in use.. As a matter of fact it is our support for growing hops and serves for additional storage for our beach finds and can double for a sun shade by draping a canvas tarp over it in hot weather. We even use it for raising crab traps and miscellaneous gear in and out of boats.
Obviously not everyone has a beach house built over the water, but the basic principles here could be applied to many different situations where a boat lift would be needed from lakes to rivers.
Step 1: How Is This Different From Other Arbors or Garden Trellises?
There are many great and time tested designs for garden arbors. However the physics of a boat lift trellis are a little different and there are a few key elements that you need to pay attention to in order for it to work properly. A traditional garden trellis only has to hold itself and perhaps some vines or other plants and the weight is distributed evenly. A boat lift trellis on the other hand will be handling more weight when its lifting a boat all focused on one end and can act like a see-saw. It's therefore extra important that a boat lift trellis be very well bolted and anchored to deal with the counter balance effect and that they don't extend too far over the water which will weaken support.
You will see in later steps how we notched and cross supported our trellis specifically to help deal with the variations in weights and the stresses of cross stresses that come with lifting small crafts.
Step 2: Inspiration
As we mentioned earlier the internet is littered with thousands of garden arbors and trellises for inspiration. Check out THIS Garden Arbor by macarch or THIS Wooden arbor - simple DIY project by skiedra which even comes with blueprints. You will need to come up with a design that fits your taste and fits in with your location. Obviously building codes vary wildly by location so make sure you check with your local building office before settling on a final design.
It is important to remember that although they may look similar there are some basic design differences between a basic garden arbor and one designed to lift small boats.
Step 3: Tools
Depending on your anchoring needs, its possible to make this project with a few simple tools.
Circular Saw with a Carpenters Square or Miter Saw
Drill with various bits for pre-drilling holes and securing screws
Wrench for tightening bolts
Step 4: Materials
Keep in mind that designs will vary from location to location. We built ours largely from Cedar because we were able to scavenge some from a fence and it is more environmentally friendly, but Pressure Treated wood is also acceptable outdoors.
You will need at least 2 ea exterior grade 4x4 posts (4 ea if it is free standing)
At least 4 ea exterior grade 2x6's the length of your trellis (2x8's may be required depending on the length of span required)
At least 2 ea exterior grade 2x6's for cross bracing
A variety of exterior grad 2x4's for additional bracing
Either galvanized or stainless steel screws and bolts for the main structure and several for the pulley supports. Stainless works best near the ocean but also costs more and is more difficult to find.
At least 4 pulleys or more depending on your design
Adequately sized exterior grade rope
Paint or stain as needed
Various hinges and locks if also building a large gate
Step 5: Anchoring and Design
In our case we were able to saw though our deck and anchor our trellis to our main support piers. Unfortunately it is difficult to give general advice since every deck or dock is going to be built differently and the requirements are going to vary wildly depending on location and climate.
It is safe to say that this is going to be the step you will need to figure out first and then design your boat lift trellis around your foundation points. If your dock is built on 4x4 pressure treated piers it may be possible to replace them with longer 4x4 extensions which will serve as the main masts of your trellis.
If one end of your trellis ends up being secured to a building via a sill plate, it is important to make sure this is structurally anchored to your building.
Our original idea was to mount our base as close to the edge of the dock as possible to allow the most overhang for lifting boats. However in reality we ended up needing to mount our bases around a foot from the edge.
Step 6: Creating a Gate
We needed an access area from the deck that was large enough to handle small boats. We were able to accomplish this by cutting away a section of the railing and re-purposing it into a large gate by strengthening, cross bracing and adding gate hardware. We also added a small rubber wheel along the bottom to help it swing open. As a bonus the gate matches the original railing and fits in well with the rest of the design.
Step 7: Assembling and Cross Bracing
We started with a typical railing around our deck and cut an opening the width of the space between our main supports. Remember to be your own best recylcer, we were able to salvage this railing and reconstruct it into a new gate that covered the width of this opening adding both safety and diversity to the design.
Also note that we cut notches in our top supports that help hold the entire structure more stable with the added strains that will inevitably be put on this structure when lifting boats and bolted this all together using either stainless steel or galvanized bolts.
Step 8: Block and Tackle
The use of pulley's to lift heavy loads is one of the oldest technologies known to man so I'm not going to go into this too much here other than to say that the pulleys are the key to making this a functional boat lift and there are several ways to set these up. Our system works okay using two pulleys but can be a struggle for one person lifting a boat. Adding additional pulleys would ease the amount of strength needed to lift a boat could possibly put more strain on on the supports. You are going to have to work out your own best method depending on the size of your craft and supports. Keep in mind that once again stainless steel fixtures will last the longest in a salt water environment but will cost more. You may be able to make your own using things like discarded lawnmower wheels etc.
We also installed galvanized cleats at several different areas at this point so that the boats could easily be tied off at many different locations. This has helped a lot with various sized crafts being lifted at various heights and tides.
Step 9: Problems and Solutions
This is a pretty basic boat lift but we have had to work out a few kinks with the system over the years.
Probably the most important thing is to make sure your lines do not get tangled when you are raising and lowering the lines. This may take a bit of skill depending on the water level but a twisted line can make it almost impossible to raise or lower a boat.
This system works best with narrow and well balanced boats like kayaks, but it is possible with wider rowboats. Make sure your load is balanced and that the two areas for attaching lines are as close to the center of the boat as possible for good balance.
Step 10: Enjoy!
Our boat lift has greatly added to our boating access during many kinds of tides and made it much easier to get on and off the water quickly. I hope that we have inspired you to try something similar and enjoy your time on the water! Always remember what Kenneth Grahame wrote in "The Wind in the Willows"
“Believe me, my young friend, there is nothing - absolutely nothing -
half so much worth doing as simply messing about in boats.”