Project boat attempt

[Jacob]

I'm thinking of re-doing a 26' steel boat for use on the Great Lakes. The boat was built in WIsconsin in the 50's and used as a grocery delivery boat for the Great Lake freighters and was powered by a 8 cyl. gas engine. Nothing is salvageable except the hull itself, and that needs repairs. I'm hoping to turn it into a comfortable little cruiser with a cruising speed +/- 8 - 10 knots. I'm hoping to replace the motor with a fuel efficient diesel engine, much like I have on my 27' sailboat. How do I select engine & prop size for the boat. Where do I start?

[messabout]

A valuable resource for you will be two books by Dave Gerr. One is: The Nature of Boats. The other is The Propeller Handbook. Both are loaded with good information that you will find useful on your project. You will surely save many times the cost of these books with the use of the information contained.

[Jacob]

Originally Posted by messabout

A valuable resource for you will be two books by Dave Gerr. One is: The Nature of Boats. The other is The Propeller Handbook. Both are loaded with good information that you will find useful on your project. You will surely save many times the cost of these books with the use of the information contained.

Thanks,

'nature of boats' has been ordered

[mydauphin]

REMEMBER, it is a displacement boat, Water length determines speed. You should be able to figure out displacement, beam, lwl and speed. Then work backward to get HP. Shouldnt be alot. Then give yourself a 25% margin. Should be in 20 - 50 hp range with diesel and a big prop.

[PAR]

Jacob, when designing a steel hull, an accounting for plating corrosion, over the expected life span of the vessel, is preformed. This lose of thickness and strength is addressed in the hull shell plate scantlings. If your 50(+) year old steel hull has seen considerable neglect, it's very likely the hull shell will need repairs at best, possibly wholesale replacement in seriously corroded areas.

Assuming a LWL of 24', you can muster a displacement speed of 6.6 knots (@ S/L 1.35). If the hull shape and power available will permit, you may be able to exceed this LWL limited speed. To reach displacement speed you'll need relatively small amounts of HP, but to push much past this point, you'll need a kind shape and globs more power. Again, assuming you have a conventionally shaped hull form, 10 to 15 HP will likely get you to displacement speed easily, possibly less, depending on weight and shape. To get to 10 knots you'll need to push a little over 2 S/L.

You should have a steel experienced surveyor look her over, before plopping a bunch of money in a tired hull.