Outboard Powered Trawlers

[Larry M]

What are you think’in Larry re the engine room space? 1200 gallons of gasoline?

Beer and maybe a few to several hundred gallons of fuel? I’m not sure he needs more? If the boat is used as the majority of our boats are in that size range, he may have plenty of capacity? For a weekender or day trips? I have no idea but maybe a 100-200 mile range?

We use to have a Chris Craft with a 350/250 hp(?), inboard granted, but only carried 50 gallons of gas. We’d leave from Tacoma for Port Townsend or Laconner, based on the trip for the first fuel stop. Once I thought we could make it to Port Angels. We just made it past the USCG Station and when we ran out of gas.

Capacity and range, it’s all how you use the boat I guess.

 

[Scratchnsaw]

For comparison and my thinking and observation, IMHO the GB 42 footer weighs in around 35,000 lbs. A center console Yellow Fin 42 weighs in around 16,000 lbs. You will be attempting to move a much larger mass, vertically and underwater mass by using even the current state of the art outboards. By themselves the outboards will need higher rpms to move and turn the boat from a standstill, not withstanding the any current that's present. So you will have more turbulent wash simular to what you would be doing with an outboard in a barrel.



While the outboard may send water outward, the boat still needs to move away at a greater rate than possible using traditional outboards these days. Your wheels are only so big. I observe this will a kicker on my older sailboat in a simular setup with an undersized motor for the size of the hull The newer Suzuki outboards are using duroprops now days. This is showing an increase in performance for the newer center console boats in the repower from even the 300 hp. Yamaha outboards.



Now there are set ups with thrusters mounted in the sides of transom brackets, some built into the hulls of the newer builds that will assist with the outboards to maneuver the boat better along with the standard bow thruster setup that’s fairly common these days. .But if you truly want a bastardized GB, take those inboards out and add the outboards.

 

[Scratchnsaw]

And for kicks, if you are looking for some reading during the winter time,,,


https://www.thehulltruth.com/boating-forum/541832-64-viking-twin-outboards.html


Now where is my bag of popcorn..

 

[FF]

A conversion to a modern small gasoline engine would seem simplest and still be effective.

" IMHO the GB 42 footer weighs in around 35,000 lbs."

This is about 15 tons of displacement so 30-45HP is all that is needed for normal displacement speeds.

Many small car engines can provide this level of power with good fuel economy.

A diesel in fine condition might be able to make 20HP from a gal of fuel, if run at just the right speed and load , but most produce 15 hp/gal.

This fuel burn is now in the range if a tiny turboed gas engines .

An custom bell housing would need to be created to hang a marine tranny with a deeper reduction than the diesel.

The boat would be lighter quieter and with the low cost of maint compared to a diesel (and cheaper fuel) there should be no resale problems.

Yes a marine air cleaner , starter and alt would be required , as well as a bilge blower.

 

[Scratchnsaw]

For an example, this boat finished off at 5200 lbs without rigging, IIRC.

Trailer & Weight

You can look at the speeds and fuel consumption with the 60 hp.
Impressions

So pushing a hull that weighs just under 7 times the amount still leaves you with a "DOG" from the original setup.