Tugs, Trawlers, and Planing Hulls!!!???

Tell me which shine in what application. Opinions ok but some facts also! What's the difference between tugs and trawlers? Talking 26-30 feet long.

Re: Tugs, Trawlers, and Planing Hulls!!!???

I'm pretty sure most tug looking boats 30' and under are just trawler hulls with different cabin designs.

Displacement hull is the term your looking for.

Re: Tugs, Trawlers, and Planing Hulls!!!???

Displacement hulls will give you great fuel economy but go sloooooow. Planing hulls have to be lifted up onto the water and so generally require more power. They go faster but of course suck much more fuel to keep up on plane.

Definitely critical things to consider if you plan on long range cruising. With displacement hulls, the journey is definitely the focus, versus getting to a destination quickly.

Re: Tugs, Trawlers, and Planing Hulls!!!???

And there is a semi-displacement hull in between that kinda does both, but neither jobs as well as the specialty hulls. Then there are catamarans and a few other variants. And then there are variations within the variants.

Displacement hulls suck in bass tournaments. Planing hulls make poor Supertankers. Semi-displacement hulls don't do well at the drags.

Re: Tugs, Trawlers, and Planing Hulls!!!???

QC nailed it. 26 to 30 foot "tugs" are almost always semi-displacement hulls with traditional tugboat-style superstructure. There aren't many true displacement hulls of that size because displacement hulls are limited in speed by their length and longer hulls are faster. Not many power boaters want to limit their speed as much as a 26-30 foot displacement hull will.

To calculate displacement hull speed simply take the square root of the length at the waterline in feet and multiply it by 1.34. The answer is the theoretical maximimum displacement speed in knots. Displacement hulls boats can usually exceed this speed without planing, but they suffer a huge decrease in fuel economy when they do. Semi-displamcent hulls trade some economy at low speeds for the ability to get barely on-plane and double or triple their displacment speeds without as big a hit in economy as a displacement hull plowing at 1.5 times displacement speed.

Re: Tugs, Trawlers, and Planing Hulls!!!???

Good posts above. In displacement hulls, the power roughly goes up by a cube of the speed. Fineness and prismatic ratios have an affect on power and speed. Destroyer vs fleet oiler.

Re: Tugs, Trawlers, and Planing Hulls!!!???

interesting.... I love learning on iboats!!!!