a hardy homemade outboard idea

[UGLandrum]

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[tashasdaddy]

Re: a hardy homemade outboard idea

looks just like a Briggs & Stratton outboard, they do make then.

 

[tx1961whaler]

Re: a hardy homemade outboard idea

This is just a basic Paint sketch at the moment. The outboard will be able to turn completely around for going in reverse, so that eliminates a gearbox. The design is strait forward and simple to fabricate. This design could be more reliable than an production made outboard, notice I used "could", it is still a rough sketch and theoretical. But in this type of drive system, simple can be very reliable if designed properly. You know how all those manufacturers like to make products with a foreseeable life time limit, in my design it will be built "like they used to make em". I want this thing to be serving my grandchildren reliably. But don't worry, the Briggs I have has always been very well kept and I will choose a quality angle drive that is easy to find parts for rebuilds in the future.

Ummmm....Evinrude Lightwin 3 HP? Mine are still running 50 years later....

 

[kenmyfam]

Re: a hardy homemade outboard idea

http://www.briggsandstratton.com/engine_power/products.aspx?cid=7

 

[tmcalavy]

Re: a hardy homemade outboard idea

Funny how what's old is new again, every now and then...your concept is sound. It's almost a dead ringer for some of the outboard designs of the 1930s and 40s. The only thing I don't fathom is the electrical connector for lights? What lights will you need?

 

[G DANE]

Re: a hardy homemade outboard idea

I have been into a lot of crazy projects mylself, and I agree that innovation now and then comes from fooling around. Your time is your own. If the goal is to build a sturdy longlasting outboard, I doubt the B&S motor will be able to run more hours than a well maintaned outboard. The reason many of these simple build 4 strokes run for years, is the limited amount of hours they are used every year. If you mowe your lawn, lets say every week, all summer, for an hour, you will have 20 hours of service every year. In 30 years, thats 600 hrs. Do you know a lot that had a mower that long ?? Outboards run average 50 hours a year, when recreational used. Its not the wear that puts them out of service. I have known lots that have outboards with thousands of hours on them. I fully understand you feel like constructing this beast, and for the fun, go ahead, but producing something better or more sturdy will be difficult.

 

[phineas]

Re: a hardy homemade outboard idea

Look on "you tube" for homemade outboards with lawn mower motors on them. Lots of people are mating them to an outboard leg. I am thinking of trying it myself as I got a ton of part motors and I can get lots of lawn mowers at the dump. There is one on you tube where a fellow took a whole riding mower and built a boat around it but it is an inboard i guess hahahaha i loved the look of that one, it still had fenders seat and hood, no wheels and the bottom shaft of the motor went through the bottom of the boat somehow.

 

[UGLandrum]

Re: a hardy homemade outboard idea

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[ondarvr]

Re: a hardy homemade outboard idea

These types of projects are fine for the person that likes to tinker, but the real value is almost nothing if you actually plan to use it for the designed purpose.

B&S engines are built to be one thing and that's cheap. Like G Dane said, the expected service life of one is very short, and they are about as crude as they come.

The existing B&S outboard is loud and it shakes badly, plus the manual says not to troll with it or it may over heat. B&S engines are designed to run at a certain RPM, this keeps the air flow sufficient to cool it under a load.

I don't see a back a yard engineer building an entire outboard and have it anywhere near as good, or low in cost as a used Johnson or Evinrude from the 1950's to current.

 

[Lone Duck]

Re: a hardy homemade outboard idea

These types of projects are fine for the person that likes to tinker, but the real value is almost nothing if you actually plan to use it for the designed purpose.

B&S engines are built to be one thing and that's cheap. Like G Dane said, the expected service life of one is very short, and they are about as crude as they come.

The existing B&S outboard is loud and it shakes badly, plus the manual says not to troll with it or it may over heat. B&S engines are designed to run at a certain RPM, this keeps the air flow sufficient to cool it under a load.

I don't see a back a yard engineer building an entire outboard and have it anywhere near as good, or low in cost as an older Johnson or Evinrude from the 1950's to current.

And therein lies the challenge !!

 

[4JawChuck]

Re: a hardy homemade outboard idea

Honda outboards under 5 HP turn completely around and the lever flips from front to back to get reverse, might want to look at their design for ideas.

 

[Chris's CVX16]

Re: a hardy homemade outboard idea

Just a little factual change you might want to make in your drawing.

The gear set in all outboards (stern drives too) is to decrease prop RPM in relation to motor RPM. This is to get the motor further into it's powerband so it can overcome the load on the propeller.

 

[UGLandrum]

Re: a hardy homemade outboard idea

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[Silvertip]

Re: a hardy homemade outboard idea

Water cooled and designed as an outboard. Take a look at the current crop of chain saws and weed whip engines from quality manufacturers like Husqvarna. The label now has a service life number and it believe me, it isn't 50 years -- nor is a Briggs mower engine. Because an air cooled motor has been around 50 years does not mean it has been used 50 years. They are also governed at 3600 RPM and will fly apart if over reved. In looking at the drawing, I see a "gear-up" lower unit to increase prop speed. While that may sound like a logical thing to do (more rpm = greater speed) that only works provided you have enough power to twist the selected prop that provides that speed. My point is that if you want this engine to perform like a 12 HP, it must be propped and geared accordingly. Outboards are "geared-down) typically in the 2.6 down to 1.64:1 or so. Lug that air cooled motor and you are guaranteed overheat and lose of ring tension. Also, outboards are now HP rated at the prop rather than the power head so your 12 HP engine is less than that at the prop. If you intend to sell these things, better have a deep wallet as they will also need EPA certification not to mention the hoops you need to jump through for BIA certification. What you are trying to do has already been done so I would suggest concentrating on perhaps a hybrid. Power the outboard with an electric motor but use the gasser to power a generator. The 10 HP and under class are crying for that combo -- especially on HP limited lakes.

 

[steelespike]

Re: a hardy homemade outboard idea

A solution without a problem.A fun project but hardly needed.I once made a little inboard using a horizontal Briggs even a water cooled exhaust really wasn't worth the effort.
Check out the mudpuppy (?) No reverse but a pretty simple setup.

 

[nakedguydb]

Re: a hardy homemade outboard idea

hi , , . well i am going to start building a homebuilt on a old 4hp mercury leg that i have , i am using a 6.5 hp Briggs on it , i have read lots and people say that the motors with the alum flywheel dont work because you need weight to have them run right , on the lawn mower you get the weight from the blades , has anyone ran across this before , i was thinking if that is the prolbem could a person just replace the blade weight with a round steel plate on the crankshaft end and make it part of the adaptor to the drive shaft on the leg ? this motor will only be used if the main goes south and leaves me out in the ocean , i will not be trolling with it , my 40 hp suzuki is great for that . thanks in advance for any ideas

 

[nwcove]

Re: a hardy homemade outboard idea

old thread, but unless you are doing this for a fun learning experience/project, you will spend more money on it than if you were to find a 1960's era omc rbm , refresh it and then have a reliable kicker/troller. jmo

 

[nakedguydb]

Re: a hardy homemade outboard idea

old thread, but unless you are doing this for a fun learning experience/project, you will spend more money on it than if you were to find a 1960's era omc rbm , refresh it and then have a reliable kicker/troller. jmo

hi , if i was living in the states i would agree with you , but i am in panama , and can not find a good old motor here , a new 10hp suzuki is 2200 .00 bucks , hece the homebuilt , and with buying a new lawnmower and already having the leg i will be finished at 500 bucks , $360 for the mower , $20 for the leg and the rest for the bits to bolt it together ,

 

[nakedguydb]

Re: a hardy homemade outboard idea

old thread, but unless you are doing this for a fun learning experience/project, you will spend more money on it than if you were to find a 1960's era omc rbm , refresh it and then have a reliable kicker/troller. jmo

and here is a cross post form another forum i made today , hence the reason for a spare ..................well let me tell you a little story . I retired and moved to Panama , having never owned a boat before in my life had a typical 24 ft panga built , picture a fiberglass row boat 24 ft long 6 ft wide , every local fishermen has this same boat , put a 40 suzuki 2 stroke and it great on the ocean , never thought about a kicker until a month ago when the story broke here and in the states about 3 guys that went fishing one night in the bay of panama , their motor would not start to come home , the 34 yr old died first , the 16 yr old second , and on day 28 they saved the 3rd guy 650 miles from home . do a google search on this as a cruise ship spotted them 10 days into this ordeal when all three were still alive and did not stop to help them , it is in the news in the states as we speak because 3 lady bird watchers were on the cruise ship and brought it to the attection of the crew who even looked through their spoting scope at the 3 guys waving for help . I am looking for a kicker , you can get towing insurance if you want , maybe you can eat the policy as you wait , these kids caught rain water , when it rained and ate fresh and rotting fish , be careful , save your own butt because someone might not be there to save it for you , PS , there is lots of ships around panama also, seeing the panama canel is here , yet away they drifted

 

[nwcove]

Re: a hardy homemade outboard idea

ahhh, well, that does change things. some honda mowers have a flywheel and are meant to start without the blade engaged.