Help designing the TW34 (Trawler 34).

[jacquesmm]

Design a passage maker and I will buy the plans....

Cheers

Bill

It's difficult to design a real passage maker that's only 34' long but I'll try to get as close as possible.
It looks like we have two trends here: some want a fancy trawler for week-end cruises, priority on room and speed higher than displacement, others want the real ocean going thing and are ready to give up speed and some room for seaworthiness.
I may have to design two boats.

[laporter]

I may have to design two boats.

To save you from having to design three boats just stretch the hull of the TW28 25% longer and 35% wider and I'll take it from there! *wink*

Yeah, I know what your answer is so you don't have to tell me again!

Rick

[jacquesmm]

How about 50% wider? That would give a lot of room.
Sorry about the tease but it is not that simple.

[Gubbs]

It's difficult to design a real passage maker that's only 34' long but

Why does it have to be only 34 ft? How about 38 with lwl 36 ft? I think Beebe says something like 38 ft is around min for a cruising couple. Maybe you will have to design two boats after all....

[laporter]

How about 50% wider? That would give a lot of room.
Sorry about the tease but it is not that simple.

Surely you're not joking Jacques? It's so unlike you! *hehehe*

It's possible the Nova 36 is almost twice as long as it is wide!





36' LOD with a beam of 15'8", they didn't specify the weight or draft.

http://www.novatrawler.com/36pricing.html

Rick

[Salty Dog]

Hey there Dog

In the smaller tugs the funnel provides space in the stairwell leading up to what they call a wheelhouse. Otherwise you'd have to be a mini-me or whack your head! *lol* In the larger ones it has a mirror on it so you can check the progress of your bald spot!

Rick

Yes, thank you, I'm quite aware of the functionality train. It's unfortunate that the aplomb of design have chosen a very clumsy and embarrasing way of access in what otherwise is a very well designed, well engineered vessel. IMhO

Gimicks simply look the part, and eventually become a very tired part of ownership. At this investment level, it is never necessary to put a tatoo on a teat, it should do well on its own. IMhO

The Nova T, is certainly a great step forward in what I would like to see, but like me, could use a diet in the beam. She needs a better ratio, IMhO. Staysail capability/mast/boom would put her close to a "GO' for me.

Spokaloo: "Pound for pound, some of the most seaworthy boats out there, and with such strikingly salty character are the pacific fleet. Salmon, halibut, and Bering crab boats with that work boat aire about them."

Agree, with you on this, and also agree with "some". This certainly includes the strong breadth of North Sea designs (Kvaerner influenced off-shore "grocery boats"), that are more workboat, and do have a wonderful, well thought out line.

Cheers,

S.D.-

[jacquesmm]

It's difficult to design a real passage maker that's only 34' long but

Why does it have to be only 34 ft? How about 38 with lwl 36 ft? I think Beebe says something like 38 ft is around min for a cruising couple. Maybe you will have to design two boats after all....

You are correct but our initial goal was to design a trawler between 32 and 34' in the style of the TW28. I can not drop that project.
That is why I started thinking of two designs. One would be the Trawler 32/34, not a passage maker, the other one the smallest passage maker we could design.
Yesterday, I discussed the small passage maker project with Robert.
Robert works in the warehouse and also build prototypes, he is a sailor, lives aboard his boat etc.
We were looking at the Beebe book and there was double ender, a motor sailer 34' that caught our attention. With a poop deck in the style of the Nauticats, it would be great little passage maker but that's another project.
Right now we have to make a decision about the TW34.
It must be in the style of the TW28 and we will give it as much range as possible.
I'll go back to model tomorrow and see what I can do question of Cp and D/L without excess.
I will also post a graph of speed versus range taken from the Beebe book.

[jacquesmm]

Here is the fuel/HP/range curve picture that everybody should understand before asking for a little more speed. Comments in the next message.

[jacquesmm]

The curve is for larger boat but works exactly the same way for a 34 footer.
The curve marked HP is also the S/L curve.
Look at the S/L of 1.0, close to the bottom.
It gives 7 knots (bottom) and requires only 35 HP (shaft HP on the left).
At 8 knots, only one more knot, it needs 58 HP.
At 9 knots, it needs 115 HP !!!
The two extra knots require an engine 3 times bigger.
Now look at the range, the curve going towards the left:
7 knots = 3700 NM
8 kn = 2400 NM
9 kn = 1500 NM
The figures will be different for the TW34 but the proportions will be the same.
With 250 gallons at 12 knots, you may go 200 NM but at 7 knots, you may get 1500 NM.
If I designed a hull with the same Cp than the TW28, we could push it to 10 knots with a big engine but she would be very happy and have a long range like 1500 Nm at 7 kn.
To design a hull faster than 10 knots would compromise sea keeping qualities and capacity.
I'll try that tomorrow.

[laporter]

You are correct but our initial goal was to design a trawler between 32 and 34' in the style of the TW28. I can not drop that project.

Please don't drop this project. All of the previous discussions I've read on here and the what seems to be overwhelming demand for a larger more capable version of the TW28. If you follow the entire evolution of this thread it'll become evident pretty quick that there's more than 1 boat being discussed and probably 3 different boats based on the requirements for different uses. I'm probably as much to blame as anybody for not keeping to the program on this one.

Right now we have to make a decision about the TW34. It must be in the style of the TW28 and we will give it as much range as possible.

I think I've expressed our requirements a number of times but what we're looking for is a Coastal & Inland cruiser which is capable of offshore jaunts (>=200 NM) when required. The ability to cross some big water (gulf stream) and skip through the Bahamas and Carribean is how we invision spending our retirement. The Great Loop, Downeast Loop & Inland waterways are also on the agenda which entails crossing some big freshwater lakes. A Trawler style boat, although designed for extended offshore cruising is also ideally suited for our intended purposes.

We really like the style of the TW28 and hope to build it before we progress to something larger. But, having a 25' boat now we definitely know we're not going to get all the ammenities and endurance to take us where we want to go. Fuel capacity isn't the most critical (or doesn't seem to be) factor so a boat with a capacity for 600-1000 NM is adequate. More is better of course. The ability to store or make fresh water as well as adequate refrigeration are greater concerns.

So, I guess if you must make a choice on which boat to develop first it'll be (or should be) determined by marketability. Who, of your clients that have expressed interest, are most likely to build (or capable of building) a coastal cruising, island hopping or canal wandering trawler or a fully capable ocean spanning heavy displacement passagemaker? Answer that and you'll probably see where the return on your investment in developing the product (100's if not 1000's of hours) is most likely to turn a profit. You also have to weigh the viability for an amateur builder (of which we are and why we're here) to undertake and complete any one of those boats.

The TW28 is a considerable challange for an amateur builder as I believe Macca is the only one to do it so far, Yavuz's was built by a professional. I feel I will be able to build a 28 after a few smaller projects and after having done that I think I could handle a 34. Could I jump in over my head and build a bigger, heavier, more complex passagemaker? Maybe but I severely doubt it. Maybe after having built 5 or 6 boats first. I'm not saying there aren't those that can just it's not for me.

So just stretch the TW28 as discussed earlier, give it the JM signatures that make it stand out and we'll build it one day. If there's guys that want more speed offer them the option for the WARP drive! "Damn It Scotty! I said More Power!" "I canna Captain, the degribulator drive conduit is stuffed again!" "Damn Klingons!"

FWIW

Rick