switching to a trawler from a cruiser

[Baker]

Not flat enough I am afraid. I don't think that is flat enough to be considered SD...especially if that curve increases rapidly going forward.

 

[markpierce]

What does the shape of this*stern tell you?

 

[Baker]

Mark, if you went just by the line at the stern, you could certainly make an argument for a SD hull. But I can see beyond that and can tell that the bilge deepens/bulges ahead of the stern....which is what I suspect with the DF49.

 

[markpierce]

Baker.* Yeah it drops,*by over three feet.

*

*

 

[ksanders]

DavidM wrote:
Let me offer my two cents here.

Semi dsiplacement hulls are typically hard chined flat deadrise (the angle at the transom) hulls. This hull form is a little less efficient than a pure round bottom at displacement speeds. It won't roll as much but sometimes its motion isn't as comfortable as a round bottom hull due to the sharp "snap" back and forth. The rounded chine hull is a compromise between the two types- it has less snap, but it takes more power to push it past displacment speeds due to the lack of planing area because of the rounded chines.

The round bottom displacement hull can be very rolly in heavy seas, so the OP's interest in active stabilization is a reasonable choice. I wouldn't consider passive stabilization- I assume he means paravanes, because they are difficult to deploy and would only make sense on a long offshore passage.

A picture of the D49's hull form is attached, taken from a current Yachtworld listing of an 82 model located in Herrington Harbor. It is a hard chine, flattish deadrise hull.

David

*Thanks very much for posting that photo.

I wonder what the roll period of that hull is ???

Just from the photo, (with no other data) I was hoping that the hull form was a little softerr towards the after sectionss... more like for example a Willard, Krogen, or Nordhavn hull.

This desire comes directly from Voyaging Under Power, and the extensive data that was presented regarding hull form, stability, and of course stabilization.

For example I read that using active stabilization the Nordhavn 46 would roll at around 5 degrees in "moderate" sea states, and that was with a easy motion without snap to it. Thats the goal here.

Some interesting information regarding the Hattaras 48 LRC. I found a test of that hull in a old magazine that indicated that the roll period was 4.5 seconds, and the d/l ration was 380. Comparing that against the Nordhavn* 46 and at least on paper they are pretty close to each other. I know that there are other big differences between the Hatteras LRC and the Nordhavn, but the hull dynamics are close.

*


-- Edited by ksanders on Thursday 24th of March 2011 07:44:27 PM

 

[Nomad Willy]

There is a line that tells almost the whole story about how FD, SD or planing a hull is. It's called the quarter beam buttock line. The QBBL starts near mid-ship on the bottom and runs aft to the transom. It is midway between the chine and the keel. There is the outbd stbd qtr, the inbd stbd qtr, the port inbd qtr and the outbd port qtr. In a FD transom boat (like Marks) the QBBL is rather steep and the transom is out of the water. In a planing hull the QBBL is flat or very close to it. Marks QBBL is not as curved as most FD hulls but the angle is high and that makes the Coot a serious and full full disp hull. If his transom was 6" submerged the QBBL would be straighter but more importantly far less steep. That would make the Coot a semi-disp hull. And of course if the coot had a constant dead rise hull aft with a straight and flat QBBL it would then be a planing hull. There are FD hulls that have slightly submersed transoms but they all have steep QBBLs. Look back at the DeFever picture. See that the chine is totally straight aft. That would suggest a planing hull but see that the keel line is quite steep and would'nt allow planing speeds even if disp was low enough. Since the keel line is steep and the QBBL is moderate we have a SD hull**** ...not a FD. Most all trawler hulls are very simillar to the DeFever and they too are SD hulls. Only Diesel Ducks, Willards, Fishers and a very few others are actually FD. And the reason for this populairity is the stiffness of a wide hard chine hull. A 29' Ranger will feel MUCH more stable than a 30' Willard but the Ranger is less stable and will capsize more easily. And a SD trawler will need about twice as much power as a FD trawler. Also a narrow round bilge hull will hardly work the paravanes at all whereas a wide hard chine hull will feed heavy loads through the paravane rigging. Round bilge FD hulls are better suited for paravane stabilizers and stand to gain more from thier use.

 

[FF]

Interesting ,

The latest issue of Pro Boa Builder has an article that discusses resistance in the displacement mode of plaining and semi plaining hulls.

Conclusion the TRUE displacement hull (like a sailboat hull) has 50% LESS resistance than the plaining hull at displacement speeds.

So the semi displacement folks that have huge engines and SD underwater shapes are paying over 100% more to move the boat 99.9% of the time.Big over sized engines cost efficiency by the gallon too.


That sure is expensive "insurance" for the chance to "beat the storm" sometime in the boats lifetime!

 

[JohnP]

I agree the full displacement hull moves thru the water with the least horsepower.

The fact is there are not to many affordable true displacement trawlers in the 35-45 range.* There are lots of* sailboats available that would work nicely as a trawler alternative. A covered center cockpit could be a nice pilothouse, The ballast keel gives roll over protection, and roller furling makes adding sail while motoring easy to do.The sail will lower your fuel use and prevent rolling very effectively. If everything mechanical fails the sails can get you to safety.

So whats missing?* Bright interiors, large engine spaces,speed above hull speed,easy bridge clearing.

The Bristol 41.1, 43.5 and Pearson 365, 424 are good examples.

Lots of small sailboats have crossed oceans safely.* JohnP

 

[ksanders]

JohnP wrote:
The fact is there are not to many affordable true displacement trawlers in the 35-45 range.** JohnP

*That sure is correct.

What I've found*in reasonable priced production vessels is limited to:

Willard 40, Krogen 42, Nordhavn 40, 46, and The Hatteras LRC (from the data I've found)

To be honest, although I really like the Nordhavn models they are still priced above where I was considering. A Nordhavn 46, Salvation II was listed in Seattle for $360. The boat probably sold for around $300. I'm going to top out at $250 including catching up on any defered maintenance, and fitting out costs.

In non production vessels the options are greater, but the actual numbers of boats available are much smaller and the quality is often dependent on the skills of*an individual builder. The non production boats are really hit and miss even from a design standpoint unless they used a design from a reputable naval architect.

I would seriously consider a steel hull boat, and might just go that route if I find one that meets my criteria. There is for sale right now a Nelville 39 that is interesting.

 

[Nomad Willy]

ksanders,

The Nelville 39 seems to be a wonderful boat. See it in VUP. Rob Hays (on TF) may have his Willard 40 for sale and the Krogen 42 is hard to beat. If you look at steel get a surveyor that specializes in steel. Perhaps you could find a Coot for sale? And you mention the Nordhavn 46**** ....my favorite boat. Good thing they are WAY out of my price range or I'd be buy'in one of those.

And FF,

Remember*** ...I was going to convert a sail boat to a trawler.

 

[sunchaser]

Many on the Forum have DeFever 48s. IMHO, they offer some attributes worth considering vs the 49. Both vessels*have a strong following and are not often on the market, especially in the PNW. Look up the Arctic Traveller's trawler training website. Jeff, possilby the most seasoned TF member, has a DeFever 49 and it located in Alaska.

 

[akboater]

Kevin,

I made that switch, (Symbol 51 to Seahorse 52). For whatever its worth, neither one is all that comfortable running abeam.* My family owned 80's vintage Hatterases, and I was in awe of the LRC's, but I would be very apprehensive about the age. Any 30 YO boat is going to be a handful to keep working especially in our neck of the woods. I am in Whittier also (M-4, Cliffside),* Are you aware that SALSA is available in Seward at a price that is hard to believe. You could have a 60 Hatteras...., and the fuel bill...

*

Mike

 

[Nomad Willy]

David,

Are you saying the 4-53 DD has vibration issues? Hard to imagine that as they must have the same number of power strokes as a Buick straight eight. I wonder why they made the 4-53 and the 3-71 as they both have basically the same displacement.

 

[FF]

"A Hatteras LRC repowered with John Deere's would be nearly perfect though."

If you want smooth a pair of rebuilt 3-71 would cost 1/5 of a pair of Deeres.

If you prefer modern with electronic injection a pair of International 466's would be my choice , at about the same cost as the rebuilt '71's.

 

[ksanders]

akboater wrote:
Kevin,

I made that switch, (Symbol 51 to Seahorse 52). For whatever its worth, neither one is all that comfortable running abeam.* My family owned 80's vintage Hatterases, and I was in awe of the LRC's, but I would be very apprehensive about the age. Any 30 YO boat is going to be a handful to keep working especially in our neck of the woods. I am in Whittier also (M-4, Cliffside),* Are you aware that SALSA is available in Seward at a price that is hard to believe. You could have a 60 Hatteras...., and the fuel bill...

*

Mike

*Mike, nice to hear from someone else in Whittier.

I saw the Ad for Salsa on CL a couple of weeks ago. I haven't been on her but if she's in good shape thats allot of boat for the buck!

Amongst others issues a*realistic problem with her is that while I could buy her, I really don't have the resources to maintain a 60' hatteras with twin 1200 hp engines. I can't imagine the bill to re-build a 1200 HP engine.

The switch to a trawler is going to involve a switch in harbors as well. We've been in Whittier for a long time, but we'll never get a slip there for a 40'+ boat. (it took me 6 years to ger a 28' slip). I could buy a slip at cliffside for 130K but that won't leave much to buy a boat with.

Seward is the only alternative for us. I'm only a couple of years out for a 50' slip, and the harbormaster told me that transient space is not a problem.

Our favorite areas are the south sound. We love the south passages and McLeod harbor on Montague. We*rarely even stop in the north sound except to drop the shrimp pots.

*

 

[markpierce]

nomadwilly wrote:
... *Perhaps you could find a Coot for sale? ...

*I appreciate your remark.* When calling Bill Kimley at Seahorse, tell them it was my suggestion.

*

 

[akboater]

ksanders wrote:akboater wrote:
Kevin,

I made that switch, (Symbol 51 to Seahorse 52). For whatever its worth, neither one is all that comfortable running abeam.* My family owned 80's vintage Hatterases, and I was in awe of the LRC's, but I would be very apprehensive about the age. Any 30 YO boat is going to be a handful to keep working especially in our neck of the woods. I am in Whittier also (M-4, Cliffside),* Are you aware that SALSA is available in Seward at a price that is hard to believe. You could have a 60 Hatteras...., and the fuel bill...

*

Mike

*Mike, nice to hear from someone else in Whittier.

I saw the Ad for Salsa on CL a couple of weeks ago. I haven't been on her but if she's in good shape thats allot of boat for the buck!

Amongst others issues a*realistic problem with her is that while I could buy her, I really don't have the resources to maintain a 60' hatteras with twin 1200 hp engines. I can't imagine the bill to re-build a 1200 HP engine.

The switch to a trawler is going to involve a switch in harbors as well. We've been in Whittier for a long time, but we'll never get a slip there for a 40'+ boat. (it took me 6 years to ger a 28' slip). I could buy a slip at cliffside for 130K but that won't leave much to buy a boat with.

Seward is the only alternative for us. I'm only a couple of years out for a 50' slip, and the harbormaster told me that transient space is not a problem.

Our favorite areas are the south sound. We love the south passages and McLeod harbor on Montague. We*rarely even stop in the north sound except to drop the shrimp pots.

*

*I spent a number of years in Seward. Nice but seems small* unless you head across. And I agree on the south passages of PWS!*

FWIW, I got an email from the* broker on Salsa, now asking 180.

*

 

[FF]

"What does the shape of this stern tell you?"

Plaining hull , not full displacement.

Great at 15- 18K in smooth water with enough power perhaps 25K.