Are Nordic Tugs worth the money?

Baker said:

A semi planing hull is a much better ride in chop than a planing hull because of this!!!

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I have thought for years that the Ocean Alexander 42 has a planing hull. It was pointed out to me a few weeks ago that the OA 42 has a semi displacement hull! last week, In a ride off shore we encountered a "chop" that really opened my eyes! The ride was terrific! (comfortable) So far, I haven't had the boat in any 4-6 footers so I don't know how she'll handle those.

Baker your'e right IMO.

Attitude (or angle of attack) and weight for a smoother ride. But makes for a wet boat. Speed also makes a boat wet if not fast enough to push her bow up. Willy is surprisingly dry mostly because of the lack of the hard chine and speed .. mostly the latter. Balance adds to it too. Willy rises up over waves because she carries her weight further aft where there's lots of hull to support her considerable weight. Lots of trawlers have aft cabins and the wheelhouse further fwd and hence the engines (heavy) a bit too far fwd. Some W30 models lean a bit in that direction. Boats are pointy at that end where support from the sea is lacking. All chain anchor rodes aren't a plus in this reguard either.

Codger,
Looks like a planing hull to me.
What features of the OA take her out of the SD catergory?
Given enough power will this boat do 25 knots?
I'm thinking that would make her a planing hull.
From the pics she dosn't look heavy and the huge blade area of those props hints of lots of power.
Are your engines broken in yet and have you gone to WOT?

She's probably a balanced boat and quite level riding as a result. That would be a big plus for the ride. Also she's a big boat and larger boats have a beam to length ratio that is a bit more long and narrow than smaller boats. That will help keep the ride more level.

manyboats said:

Codger,
Looks like a planing hull to me. Looks like a planing hull to me, too!
What features of the OA take her out of the SD catergory? I don't know.
Given enough power will this boat do 25 knots? Yes (With 500s) I have 440s. She does 23 knots at WOT.
I'm thinking that would make her a planing hull. I agree! But the specs say she is an SD.
From the pics she doesn't look heavy and the huge blade area of those props hints of lots of power.33,000#
Are your engines broken in yet and have you gone to WOT? She has 293 hours on the engines and, yes, I've been to WOT several times.

She's probably a balanced boat and quite level riding as a result. I find this to be accurate. That would be a big plus for the ride. Also she's a big boat and larger boats have a beam to length ratio that is a bit more long and narrow than smaller boats. That will help keep the ride more level.

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I'm impressed as to how much you get out of a few photos and 1 video! I'll send you photos of my next buy before I close on the deal. (Just kidding! I'm pretty sure that this will be my last boat.)

For a 42' boat 33,000 pounds seems fairly light. On the Travelift our GB36 weighs in at 30,000 pounds. Even with a pair of 220 Cummins in them the best this model can do is about 14-16 knots I believe.

Walt, we'd really need to see the front portion of the hull as that is where it is usually deep and lacking planing/lifting area. And then the hull begins to flatten as you go aft. One of the things planing hull manufacturers employ to make the ride better is deadrise. And that is how much Vee is at the stern...or how much of it is carried aft. But the result is the same....less lift(and lost efficiency) while allowing the boat to go through the weather.

Marin said:

On the Travelift our GB36 weighs in at 30,000 pounds. .

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I don't doubt your numbers but in 30 years of owning boats over 30ft and watching the gauge on Travel Lifts, I have yet to see one that is even close to the manufacture's listed weight of 33,100# empty. (IE) My boat tipped the scale on a one year old Travel Lift at 40,000+. Even with 500 gals of diesel and 150 gals of water, (which she didn't have) plus some personal belongings she shouldn't go over 40,000#.

Baker,
Depends on where the boat rides. A "cigarette" will run at speed on just the aft part of the hull w everything fwd completely out of the water. Lots of deadrise for a reasonable ride.

A slow boat will not benefit (in this way) from increased deadrise aft.

The best pic of Walt's boat would be from abeam or just aft of that and w the camera just below the WL. We will be looking for "rocker". Or a lot of "warp" or twist in the hull .. like a GB. With straight longitudinal lines she can only be a planing hull. What's aft is 98% of the story. A CHB is close to planing at her chine but at the keel there is pronounced rocker and looks mostly like a FD hull.

With Walt's boat .. for her size .. relatively light and having straight lines aft (except a bit of the tunnels) puts her in the planing type. But in Walt's case I'll bet the "specs" are selling boats. Brokers, Builders and other sellers in this day are selling boats and frequently stretch the truth. "But the broker said it was FD".

But someone aluded to the fact that I was making an educated guess having not see good pics of the boat. Ture. but as the football flies through the air we can guess the shape of the other side. And I'll change my tune if pics are forthcoming and show that the boat has rocker ... like a NT. There is a good SD hull.

It's hard to imagine OA making a false claim here so maybe she is a SD boat. They have a lot to loose by false claims and IMO may have a case.

Baker,
Actually "deadrise" applies to the angle of rise of the bottom toward the chine from the keel anywhere fore and aft. I think you're thinking of the expression "constant deadrise" and that does apply to approximately amidships to the transom. Most all boats have deeper deadrise in the forefoot. So some warp is always present fwd in most boats especially hard chine.

Baker said:

Walt, we'd really need to see the front portion of the hull as that is where it is usually deep and lacking planing/lifting area. And then the hull begins to flatten as you go aft..

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This is the best I can do in the photo department. I suppose if you draw a straight line across the
tunnels, meeting at the center line, you get some idea of the deadrise.

manyboats said:

The best pic of Walt's boat would be from abeam or just aft of that .......

It's hard to imagine OA making a false claim here so maybe she is a SD boat. They have a lot to loose by false claims and IMO may have a case.

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This about as close as I have to what you are describing.

manyboats said:

Baker,


Baker,
Actually "deadrise" applies to the angle of rise of the bottom toward the chine from the keel anywhere fore and aft. I think you're thinking of the expression "constant deadrise" and that does apply to approximately amidships to the transom. Most all boats have deeper deadrise in the forefoot. So some warp is always present fwd in most boats especially hard chine.

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I thought I was being clear or maybe you misunderstood me. I was using the therm exactly as you stated....keel to chine. "Rocker" in a boat does not define wether it is semi planing or not. In fact, the more rocker you have, the less likely it is to plane. Let's not make this any more complicated than it needs to be. Water needs a lifting surface. Generally, the bigger and flatter it is, the better for generating lift. A flat bottomed skiff is the extreme example of this. It is also the extreme example of the way I used the term "efficient" above. The disadvantages of a flat bottom skiff are obvious...namely the ride!!! So it is up to the hull designer of a planing boat to balance lifting surfaces with respect to how the boat is going to ride. A semi planing boat will ride better than a full planing boat...in theory...because of things already stated above. It is because the lifting surfaces will transmit the bumpy water to the structure and its occupants because it is on TOP of the water where the bumpy water is. This is why a full displacement boat rides better than a semi or planing boat at displacement speeds. The full displacement boat is IN the water...not on TOP of it!!!

I would argue that Walt's boat is a planing hull. BUT, as we all know, it is not black and white.

Baker,
Certianly the more rocker you have the less likely it will plane. And in a way it (rocker) does help define planing from SP or SD. Rocker (fore and aft convex ness) is not a feature of planing hulls so it's presence testifies that the boat is not a planing hull. But you're right it's not B&W as there are some boats that change from FD to SD .... to some degree by changing their angle of attack .. and that can lower the tramsom allowing the boat to sorta plane at low speeds. The "Handy Billy" is a good example of the type. Broadly speaking though they are SD or SP.

I called Walt's big beautiful OA a planing hull. If it lacks rocker it would probably show that she's a planing hull but if she has some rocker it would prove me wrong. I don't think we'll find any rocker though.

Baker said:

Generally, the bigger and flatter it is, the better for generating lift. A flat bottomed skiff is the extreme example of this. It is also the extreme example of the way I used the term "efficient" above. The disadvantages of a flat bottom skiff are obvious...namely the ride!!!.

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John--- I fully understand what you're getting at. Our 17' Arima fishing boat is a beautiful example of the compromise dilemma faced by every boat designer. Mr. Arima, a former Bayliner engineer (?) decided to strike off on his own back in the late 70s or early 80s. His goal was to create a trailerable fishing boat that could be towed behind the smaller pickups as well as mini-vans that were becoming popular at the time, be ideally suited for use in Puget Sound waters, and be able to be driven with less horsepower than the comparable fishing boats of the time.

As people who boat here know, we don't have swells to deal with but we do have wind waves which are often fairly steep-sided and close together even if they are a just a foot or two high.

So he gave his design a deep forefoot (for this type of boat) to cut the waves. The hull then transitions rapidly to a very mild V (rocker if you will) in the afterbody with a hard chine. So a good two-thirds of the bottom is an efficient planing surface.

The resulting boat does exactly what Mr. Arima intended it to do. Its high bow and sharp, deep forefoot does a great job of cutting through the waves rather than riding up and over them. And the planing surface aft of that does a great job of lifting the boat to travel fast and efficiently over the water. His first two models were the 15' and 17.'

But..... Mr. Arima's compromise is a boat which, when put on the plane in rougher water can pound your teeth out and worse, when the waves are taken at an angle has a habit of pounding hard on the upwind (or up-wave) side at the chine. So in these kinds of conditions, you slow down and mush through it.

What I find interesting is that, apart from the absence of a keel and nearly plumb stem, the underbody of our Arima is not unlike the underbody of the hull on our GB. The Arima has a bit more V-at the stern than the GB and it has lifting contours toward the front to help the boat get on plane, but otherwise the basic underbody contours are quite similar in basic concept.

The photos are not of our boat--- I don't have any of it out of the water-- but are from an ad for one on the web and is the same model and vintage we have. All Arimas, from the 15' up to the 22' use this same hull form although it's had details tweaked over the years.