Engineering challenge lifting a 130 lbs. sailboat on top of a car.
Martin_H
Posts: 4,051
I like to sail and usually rent a small sailboat (e.g. Sunfish, Pico, Zuma) while on vacation. These are great for one or two adults or an adult and two children on ponds and lakes. Over the years I could have bought a used one for the rental fees, but for many reasons a boat trailer seems daunting. In theory board boats are light enough to be car topped, but Ive found any boat over 85 pounds is tough to lift on a car single handed. This is a problem for a boat which is generally sailed single handed.
Ive asked owners how they single hand and they always say using a trailer which is a show stopper, so I continue to rent. Ive seen two home brew solutions similar to this:
http://www.youtube.com/watch?v=B843S8Pz6xg
He basically built a combined ramp/lever which isnt a bad idea. But I figured with all the brains on the forum someone might have a better idea.
Honestly I would prefer to just buy a solution, but nothing seems to exist as it is likely too small a market.
Ive asked owners how they single hand and they always say using a trailer which is a show stopper, so I continue to rent. Ive seen two home brew solutions similar to this:
http://www.youtube.com/watch?v=B843S8Pz6xg
He basically built a combined ramp/lever which isnt a bad idea. But I figured with all the brains on the forum someone might have a better idea.
Honestly I would prefer to just buy a solution, but nothing seems to exist as it is likely too small a market.
Comments
You could have an end-loader rather than a side-loader; but I suspect it would take longer rails and might be more awkward. Less than 150 lbs. is not that much if you have leverage and two or more people.
But I forgot how to get them off at the other end.
@Xanadu, I have never seen an inflatable sailboat in action. I will have to read more.
@erco, my wife would strangle me if I modified the car like that.
On a more practical tack, use two tripods and a pole/truss to span above the vehicle and use a pulley system to lift boat - then drive under and lower onto roof rack.
Rather tall and ungainly and detaching the lifting gear might be a bit of a reach. Lightweight step-ladder might be substituted for one of the tripods to aid access. Pole
can be used as a rope hoist if it rotates too - add a crank handle at the end?
I wonder how an inflatable sailboat would hold its position in the water. A keel and ballast are generally much needed. At least a dagger board or those boards that drop over the sides, leeboards.
If you want portable, a catamaran seems really more convenient - fast, fun, and fold down to something small.
Use a pair of 8ft long perforated 1.5" sq tube. McMaster has them including the pin for $34 under item #4931T36. You'll need a hook on the car end to hang on the racks and something at the ground (bungee?) to hold them parallel. McMaster also has adhesive thick bearing tape to protect the boat from the rails. Push the boat up the ramp onto the rails
When your all done it'll fold down to two 4ft lengths. I hope it helps.
'Foldcats' are the portable catamaran and they work the best for sailing. It holds its position okay for an inflatable, that is the big deterrent with would-be owners. I was skeptical until I had a lot of fun on a lake with an inflatable. It was a kayak sailboat that was inflatable and seated two people, loads of fun!
The bottom is designed like a kayak and the sail is designed to not take enough wind to flip you. Sure you can flip it, if you don't want to flip you just let out your sail. Running with the wind is great, otherwise you're countering adverse steering with your rudder and that is about it.
I sailed a Hunter 28.8 for years in the same bay/offshore area. Got kinda lame... If you love to sail, when you get something small and portable you can go to all kinds of places and for what it's worth possibly have a lot more fun.
The original post was to put a boat on top of a car. So I'm not saying the OP should get one of these to replace a real boat, just wanted to throw it out there from past experience as a viable alternative
The lifting is the easy part, but securing it to the vehicle is a whole other story.
To lift the boat, build a rotatable boom from tubing, pulleys, and a winch, and make it adaptable to a hitch receiver.
Bruce
I have attached a new pic, which shows a better location for the winch and a decent pivot point to prevent cable binding.
EDIT: To make a nice pivot, a person could visit a local automobile scrapyard and purchase an old spindle and brake disc. The spindle could be attached to an adapter to fit the receiver hitch, and the main boom section could be bolted onto the old disc just like a tire rim. Additionally, the brake disc could be turned down to remove any unecessary or unwanted metal, leaving just the absolutely necessary components, such as bearings, races, and lugs.
EDIT #2: You could provide a lock on the pivot. Once the boat has been pivoted into postion, then lock the pivot point, secure one end of the sailboat to the upright support member of the boom, and secure the other end of the sailboat to the front bumper. You could leave the whole assembly intact for loading, transport, and unloading. Just watch out for low lying bridges and other clearances heights issues, such as the local BK.
http://www.cabelas.com/product/Cabelas-Canoe-Loader-and-Rack/700655.uts?Ntk=AllProducts&searchPath=%2Fcatalog%2Fsearch_within.cmd%3Fform_state%3Ddefault_state%26searchWithin%3Dtrue%26N%3D0%26Ntk%3DAllProducts%26Ntt%3Dcanoe%26search%3Dcanoe%26nttWithin%3Drack%26WTz_l%3DHeader%253BSearch-All%2BProducts%253BSearchWithin%26x%3D0%26y%3D0&Ntt=canoe&WTz_l=Header%3BSearch-All+Products%3BSearchWithin
That's going to be a whole lot of torque acting on the receiver. Better make sure it's up to the task.
Please explain your theory.
Okay...
130lbs + weight of lifting mechanism ~ 200lbs.
Distance from attach point of hitch receiver to center of load = ~ 7ft
200lbs * 7 = 1,400 ft lbs of torque. That's quite a bit, especially considering that many hitches have a limit of a couple hundred pounds of tongue weight - and it is not accounting for very high momentary loads due to bouncing. A light (or even medium) duty receiver may not be up to the task.
I went to Xanadu's linked website and saw that they are selling Snarks. They similar to a Sunfish, but the hull is a sandwich of ABS, Styrofoam, and ABS which weighs 50 lbs. While not as durable as fiberglass, this is well within my ability to load singlehandedly, so it is something to consider.
@bee_man, my boat rack lets you slide the boat forward, so you only need to pick up one end and push. It achieves roughly the same thing. The problem is that the Sunfish is heavy compared to a canoe.
You could buy a gym membership ...
-Phil
After a bit of research, I would have to agree, but I would not be afraid to attempt lifting with the receiver on my truck, however, using the lift as a securing and transport device, might not be the safest idea. One must also consider the tensile strength of the lugs. It would definitely take some thought to make it safe and secure for both lifting and transport.
I respectfully wish to disagree with the following calculations:
"Okay...
130lbs + weight of lifting mechanism ~ 200lbs.
Distance from attach point of hitch receiver to center of load = ~ 7ft
200lbs * 7 = 1,400 ft lbs of torque. That's quite a bit, especially considering that many hitches have a limit of a couple hundred pounds of tongue weight - and it is not accounting for very high momentary loads due to bouncing. A light (or even medium) duty receiver may not be up to the task. "
The 200 lbs is acting vertically downward on the ball. The 7 ft column, under just this loading, should not then produce a 1,400 ft lb bending moment. However while loading the boat there may well be some side load introduced which would put a bending moment on the ball if the column is rigidly attached to the ball. But I cannot see how this moment could add up to 1,400 ft lbs. Am I missing something?
I can see where there could be a wealth of ideas for loading a canoe/dingy sized boat on a car top. I have used a roller arrangement to support half the weight of an aluminum canoe; then lifting the remaining half and rolling the canoe forward.
Might I also suggest a folding kayak or other sailing craft which could be disassembled.
Allow me a little humor to end with. The project should at least have a Stamp-based controller. How about a smart winch?
cheers, David
Oops.
I was replying to the wrong design. Yes, if the configuration is a boom with a 7 ft horizontal arm then there is a 1,400 ft lb bending moment on the ball; which would have to be rigidly attached to the vertical member.
Sorry.
David