building plate ally boat

[boatboy72]

hi all i plan to build my own boat about 36' monnohull planing or maybe semmi.

thinking about a cathedral hull just wundering what your thoughts or experiences are on stabillity and performance of this type of hull

[Ilan Voyager]

This link will give you a short and exact apreciation about cathedral hulls.

http://en.wikipedia.org/wiki/Cathedral_hull

It's complicated and time consuming. Very expensive also. Very heavy. Excellent pounders if you want to be shaken. A lot of wetted surface so it requires extra power. Stability is not bad like any almost square (wide boat). A part some river fishing boats the cathedral hulls have fallen out of favor for good reasons.

If you want extra-stability and efficiency you'll get better results with a cata. Well designed cats use about 1/2 to 2/3 of the power of a monohull for the same speed and (moderate) weight.

A simple moderate vee (around 12-15 degrees) hull with sprayers is a good compromise simplicity/results/power requirement. Deep Vee hulls need a lot of power, and may have problems of stability (chine walking).

What the speed you want? you talk about semi displacement...15, 20, 25 knots? what's the use of the boat?

[boatboy72]

yes voyager i think what you say makes sence and that a moderate vee of around 12-15 degrees would suit me better a planing hull would be nice but at the same time comefort is inportant dont want a bone cruncher.

have been in some boats that when you cross a wave they roll and turn suddenly i think this is what your talking about when you say chine walking and i dont like it some boats i have been in dont do this but was to yung to know the difrence in hull design

i have said 36' as i feel that this will put the waight that i feel is needed in an ally to help it punch into a wave instead of bouncing off it (comfort) as i would like it to be universil for family fishing trips or diving trips even comercial if the op arrises .

[FAST FRED]

In building alloy boats the big problem seems to be the equippment required and skillset required for good welds takes time , cash , and training.

What is the current opinion on simply riveting the hull?

A good air supply and a $75 rivet gun with $20 rivet trimmer would seem to be all that's needed.

FF

[boatboy72]

36' thats a lot of drilling and riveting