Trawler Concept

[mackid068]

Hi all! I have a trawler concept in mind. It is a Nordhaven-esque trawler intended to have light to moderate passagemaking (only to Maine and back from Long Island Sound) capability. It WILL NOT, NOT, NOT look like, in the words of eminent yacht designer Ted Brewer, a "rocketship." My intention is to have it look good for as many years as it can, give it a modern touch on a classic look. It's specs are as follows:

LOA: 32 ft.
LWL: I'm not sure but probably 30 ft.
Beam at Widest: 12 ft. (Maybe 14')
Displacement: Not sure how to figure this out
Hull: Full (heavy) displacement, full keel, double hulled fiberglass with composite reeinforcements or single layered steel
Powering: Diesel: 32 b.h.p. (if this is enough?)
Rudder: Probably doublehung with a large aperture.
Drawings to come!

My questions:
1. Is 32 b.h.p enough for a boat of this size?
2. How do I figure out displacement?
3. Anyone have any drawings to aid me?
4. Full keel...is it a good idea?
5. Is a 12-14 foot beam ok for stability (I want to have a stable boat even at the cost of speed)
6. What is a reasonable speed? How about 10-12 kts?
7. Does anyone have any engineering/safety problems with aft house (no open deck on top of it)?
8. Anything else?

Essentially, this design is intended to be an anti-rocket ship boat for the rocketeers.

(Rocket ship/rocketship=Eurostyled boat)

PLEASE RESPOND EVEN WITH IDEAS, ADDITIONS ETC FOR ANY ASPECT OF SUCH A BOAT!

[fcfc]

D/L ration = (D/2240) / ((L/100)^3)

D displacement in lbs. L length in feet.

D/L under 100 = ultralight.

D/L over 300 = heavy.

a D/L around 200 gives you about 15000 lbs displacement for a 32 ft boat.

hull speed = 1.34 sqrt (LWL).
7.3 kts for a 30 ft lwl.

So at 12 kts, you are on the start of planning.

132 hp should be better than 32 hp (one hundred more,perhaps even more).

nordhavn (except the 35) are all limited to hull speed.
The 35 is semi planning, but it has more than twice the power of the 40 and weigths less than half.

[yipster]

Essentially, this design is intended to be an anti-rocket ship boat for the rocketeers. (Rocket ship/rocketship=Eurostyled boat)

mackid068: i live in europe and like rocketships, dont hurt me please.

for your questions i suggest a couple of searches (button above) to get some basics.
you can also visit trawler sites, check / compare specs etc.
good luck with your anti-rocket ship boat

[mackid068]

Thanks very much. Oh, by the way, I love Europe, despite the fact that I live in a warmongering nation.

Why not consider a power cat? There are already some power cat designs with a "traditional" appearance....Could achieve the speed you want at very low power compared to a heavy displ. monohull.

[mackid068]

Hmmm...I dunno, but if you could find some websites or names then I could look up this information. Also, from an ease of use standpoint-even with bowthrusters (are they on cats?), cats are probably hard to dock even in a moderately confined area. Also, I'd like to limit costs as much as possible, so a cat is unlikely, but perhaps, if I am convinced, I'd give it a try.

068, see the April/May issue of Professional Boatbuilder and /or check out:
http://www.chriswhitedesigns.com The boat featured is not a trawler yacht but illustrates Chris Whites belief in displacement power cats having speed(30knots on a 32' X 12.3') and efficiency.
The boat is the Buzzards Bay32cwd built to a Chris White design by Multihull Development ( http://www.mdcats.com )
And there are many other builders of power cats-both displacement and planing- you can find with some research.

[mackid068]

Thanks for the link. I really do like the style of the Buzzard's. Nice, traditional yet modern.

[PowerTech]

essentially devoid of all culture That is not true.

[FAST FRED]

"I love Europe, despite the fact that I live in a warmongering nation essentially devoid of all culture."

The Culture of the USA is what allows imbeciles a computer.

Having spent lots of bucks in the last century to FREE over a billion folks should be enough Culture, The Culture of Liberty!

If you prefer the culture of License , Ill get the 1 WAY ticket to Eurowimpland for ya!

Good riddance to ignorant trash,

FAST FRED
__________________

[mackid068]

Trash? Hah. I don't wish to annoy anyone, but I dislike the current administration. I thought that was clear. By the way, the United States is better in many respects:

1. Tax system (though it needs alot of help)
2. Written Constitution (unlike much of the world)
3. Bill of Rights (needs improvements, but it's pretty darn good)
4. Last but not least, the United States Navy and USCG!

[PowerTech]

Wanabe

[mackid068]

Sorry? Please elaborate. Oh and by the way, how much diesel power is needed for a full keel, full displacement hull boat with a displacement of 15000 lbs. (As I see, PowerTech, you are a marine diesel mechanic and I thought you could offer some sort of insight)?

[clearwaters]

I second the one way concept Fred. But 12 kts on 32 hp not bad. Learning to face up to the real world and find it takes horsepower to go fast. Let alone lots of cash for the fuel. GS

[fcfc]

What my own spredsheet gives for 30 fr LWL, 15000 lbs

D/L = 250
Hull speed = 7.33 kts
Max displacement speed = 8.14 kts

7 kts = 18 hp
7.5 kts = 22 hp
8 kts = 28 hp
9 kts = 39 hp
10 kts = 55 hp

This mirror like water, clean hull and prop, no wind. (theorical conditions).
Safe to at least double for non theorical for wind, waves. Even more if you want to go winward in 30 kt wind and associed sea state.

Efficiency propulsion assumed 50%. not exceptionnal, but correctly designed propulsion system.

The boat weigth is ready to sail weigth. (crew, filled tanks, gear etc ...)
for info, 9 kts @ 20000 lbs need 52 hp.