23' car roof jon boat

I'm working on it.

 

don't be picky...

 

This boat is nice but it is infected by boatbuilding.
Why those humanoid robots go by the river ?

 

FAO fishing boat design https://www.boatdesign.net/threads/fao-fishing-boat-design.27661/
BDNet is a mine of ideas and knowledge. Sometimes it's hard to dig down.

 

I know and like it. It's not that type of water. Sand, stones.
Let's say 15" of water make me happy.

 

Sand is no problem nor gravel type rock, rock ledges however are a different matter. If I had a similar situation here and couldn't use 4 canoes and muscle (my first choice for years but I am starting to age out) I'd find an old jet ski and cannibalize the pump and motor and use it as an add on if sanity didn't strike and I used a trailer. If used jet skis aren't available I'm out of ideas but would admit to a bit of envy.

 

There are jet OBs. It is relatively easy to swap OB for jet OB.

Rumars had the idea to hang two OB on the transom, one jetOB and one propOB.

With this boat I focus on normal propOBs. It has to be fast.

Complicated transom makes me want a cut boat. Too much work with mounting engines and steering.

2m stern part with engines will be one piece and second part will be 5m bow. Much easier boat launch and loading . Hign loaded conn need to be smart.

 

A jon that size would weigh around 1000 pounds for just the bare hull. A cargo canoe would be about 500 pounds. Below is a link to an 18' cargo canoe at 195 pounds. If you scale length, beam, draft, and thickness by 23/18.3, you get about 500 pounds, and aren't far off your desired dimensions. But you still aren't putting it on a roof. The good news is you can push it with a tiny outboard - 3-5 hp.

Getting back to jon style with a 40-60hp OB, it's unclear why you would worry about the cost of a trailer at maybe $4000 for a basic steel single axle trailer when the boat will cost you 20-25k to build and rig. For another perspective, most trailer makers recommend a dual axle trailer for a 23 foot boat. Single axle is pushing it a bit, but they are available. So no, you aren't car topping it.

Freighter series | Albany 18' https://abitibico.ca/en/products/serie-freighter-albany-18?pr_prod_strat=collection_fallback&pr_rec_id=0f3b1ef98&pr_rec_pid=5974024945815&pr_ref_pid=5968550953111&pr_seq=uniform

 

How about something sorta like a normal loading trailer but sits ontop of the van's roof, and has a frame that slides out to allow the boat to slide into the water directly?
I'm thinking with a 24' jonboat its still going to be hard to get it from land to water.

 

Transport position of the hull is upside down for good CX .I need to rotate boat somehow.There are also side loaders.

 

They want to sell you another axle as it makes them money. Length is not the criteria for having an extra axle, only weight. Have transported 30ft boats on single axle trailers. FAR easier to move around than tandem axle.

 

My uncle used to go bushwhacking in Ontario with a group of fishing crazies back in the 70s. They had an old Southwind camper and cartopped two square stern 19’ canoes in, but they had like 4-6 men to get them off the camper and after they did it once they stashed the canoes in the bush for the return trip. Jim said it was hard to get them off the camper.

They didn’t use much hp on the back. In order to make the boat light; the transom cannot serve much thrust.

There is a lake in Minnesota where no motors are allowed, well thousands actually. One year I decided to go up and take a 10’ aluminum boat. Weight about 100 pounds in the back of my truck. Got to the landing 250 miles away and got the boat halfway off and really did a number on my back. Barely got it back on and drove 5 hours home.

The SOR or constraints here are not attainable. The logic of cartopping a boat with 100kg power is flawed.

Change the spec to a trailered design. The engine and its fuel require a well built transom and hull interface.

Or change the hp spec.

By the time you custom build an articulating frame on a suv or truck to assist with unloading this hull; you’ll have way more $$ in than a trailer.

 

Weight isn't the only consideration. Transport speed and distance also factor in. Twin axles are more stable at high speeds. They help lower cg a bit, and make towing with a light tow vehicle a bit safer. And having a blowout on Alligator Alley at 2 am with a single axle trailer sucks. I had to drag the trailer 1/4 mile in the middle of the tire change because of the gators closing in.

 

Yesterday's idea about the division of
5m bow part / 2m stern part. Maybe 4m bow/ 3m stern is a better idea. Roof part will be bow. 3m stern part in normal position at the bus/truck bed , with engines on transom . The issue of connecting both parts remains.