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Old 04-25-2012, 11:41 AM   #141
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Longcourse,
100 hp on your boat = about 3 hp per ton. Assuming you have a WLL of about 55' your hull speed should be about exactly 10 knots. And w 230 hp on tap and if using 100hp you're at about 47% engine load. Your hull is long and (I think) rather narrow (like the Dashew boat). The power to drive your boat through heavy seas should be low and your windage is very low so you should'nt need much over disp speed power and that seems to be 100 hp so if I were powering this boat I'd opt for about 165 hp or a tad less. Hopefully your 215s are most efficient at about 50% load but most engines are most efficient at about 80% load. I think. Tom are you here? What say you? So not only is your boat a very excellent design it seems to be efficiently powered. I would like to see a picture of your boat at right angles from the side. Out of the water of course.

Mark, Marin,
Of course your rudders are'nt shaking. Your boats are in excellent condition and the rudders are solidly mounted. BUT.....if any of your rudder bearings were loose there would be plenty of shaking. The water slung off the ends of your propeller blades are trying to shake the bottom of your boat too. If your boat light and flexible right above your propellers you will feel the vibration there too and most likely through the rest of the boat as well. The rudder and the bottom of your boat right above the props will be hammered by the propeller wash proportional to the closeness of the parts. Propwash is a bit like a hydraulic jackhammer. And no Marin....the boat was not designed to be beached on her propeller shaft keels. The "keels" are there almost entirely (or entirely) to support the propeller shafts. And yes the propellers have been removed. I'm assuming the faired prop shaft struts or keels are of minimum size (area) to minimize drag. It looks like they may be skewed a bit to conform to the flow of water under the bottom of the boat. The more I see here the more I like.
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Old 04-25-2012, 01:11 PM   #142
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Side photo

front one and also section of our rudder.
Our lw is 60' and our beam at wl is (around) 14'4"
Sure to time 110 hp is enought
because actualy as wrotte before we need less than two time 50 hp
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Old 04-25-2012, 02:01 PM   #143
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Quote:
Originally Posted by Art;
Did your precautionary engine shut-down last for many hours... to where you felt it necessary to tie off a shaft for trany
Our shaft log is cooled/lubed by water picked off the engine's raw water cooling system. No running engine, no cooling water to the log and it will quickly overheat and severe damage will occur to the shaft and the log. So if an engine needs to be shut down the shaft must be locked before continuing on the other engine.

Shaft logs cooled/lubed by a pick off from the engine's raw water system is not an uncommon arrangement.

So while our BW Velvet Drive transmissions can be freewheeled "at trolling or sailing speeds" as stated in our BW manual we can't freewheel a shaft exxept at extremely low speeds and even then the log and shaft heat up considerably.
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Old 04-25-2012, 05:06 PM   #144
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Originally Posted by longcours62 View Post
front one and also section of our rudder.
Our lw is 60' and our beam at wl is (around) 14'4"
Sure to time 110 hp is enought
because actualy as wrotte before we need less than two time 50 hp

I am still back in trying to see/understand where the shaft prop come through/out. So does the prop shaft go through the twin keels? Are the twin keels strong enough to support the weight of the boat? Do they also effect the stability/roll of the boat?

It does not take much HP to propel a boat at hull speed through the water. The DD 671 is 165 hp, and I figure at hull speed, 7 to 9 knots only 75 to 100 hp is required.
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Old 04-25-2012, 09:30 PM   #145
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PhilFill, wrote ..."Are the twin keels strong enough to support the weight of the boat?"
Very very doubtful I'd guess. I do'nt think this boat was designed to be careened.
longcourse,
Close enough. I can see the QBB lines aft and see that it's quite raked and thus steep at the keel (or on center line) and very close to flat at the chine. So the QUARTER beam buttock line is still a moderately steep so I think I was right in the first place as I recall saying it was not quite a FULL disp hull.....in other words it's not as full a disp. hull as it could be. It's better ....I think, than most full disp hulls and the smaller the boat gets the better the hull becomes until it's so narrow it lacks the stability to be of any general practical use. I would love to change Willy into a boat w this hull about 34' long. I'd probably want to add some ballast but the result would be far better than Willy in my opinion. I wish there were 35 to 40 yr old trawlers w a hull like this as I'd probably buy one. Thank's so much for sharing longcourse62.
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Old 04-26-2012, 01:18 AM   #146
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(Willard 40') full displacement
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Old 04-26-2012, 03:30 AM   #147
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The propellers

Quote:
Originally Posted by manyboats View Post
PhilFill, wrote ..."Are the twin keels strong enough to support the weight of the boat?"
Very very doubtful I'd guess. I do'nt think this boat was designed to be careened.
longcourse,
Close enough. I can see the QBB lines aft and see that it's quite raked and thus steep at the keel (or on center line) and very close to flat at the chine. So the QUARTER beam buttock line is still a moderately steep so I think I was right in the first place as I recall saying it was not quite a FULL disp hull.....in other words it's not as full a disp. hull as it could be. It's better ....I think, than most full disp hulls and the smaller the boat gets the better the hull becomes until it's so narrow it lacks the stability to be of any general practical use. I would love to change Willy into a boat w this hull about 34' long. I'd probably want to add some ballast but the result would be far better than Willy in my opinion. I wish there were 35 to 40 yr old trawlers w a hull like this as I'd probably buy one. Thank's so much for sharing longcourse62.


Our sterntubes pass in the "twin keels" but they are not twin keel because they are lot aft.
As you can on the pages of number above you have 41 section from the bow to the stern
the "twin keels" begin at the number 28+ and finish around 33.
When we stay ashore or for the tide, the main weight of boat and the main point of contact (if not A vicious rock ) it is between N+ 16 and 18 this point is very strong : watertight bulkhead and pillar (200X200X10)for the mini mast (but sized for an eventually normal sized mast ,just in case and the bottom of the hull at this place is near flat and 1 m wide , the plating of the bottom is 16 mm thick.
Aft it si the 'fin ' who protect and support the rudder.
The base of the "twin keels" at this moment touch the floor
And for more stability we put our daggers board down and block them in this position.
We need nothing more for stay ashore.

For the ballast we have already 6300 pounds and before we had mainly sailing boats it is why we concentrate (as possible) the weight and design a relatively low profile .
It is why we got a (too?) big stability with short roll period...
When we roll in moderate weather we are thinking may be it is a mistake and when we are in bad weather we are thinking it is a good idea
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Old 04-26-2012, 05:04 PM   #148
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It looks as your boat has hard chimes which would help dampen the roll. Where as the Eagle hull is round, but the keel/bilge is filled with concrete, the tanks and engines are down low, so like your boat most of the weight is down low.

So where are the daggers and how do they block in place?

I am surprised that you boat’s bow wake is flared out which seem to indicated you are going fast than hull speed? So what is the max speed? The Eagle can reach 10 kts but we are pushing a lot of water as shown in the avatar picture.
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Old 04-27-2012, 03:00 AM   #149
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Until now

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Originally Posted by Phil Fill View Post
It looks as your boat has hard chimes which would help dampen the roll. Where as the Eagle hull is round, but the keel/bilge is filled with concrete, the tanks and engines are down low, so like your boat most of the weight is down low.

So where are the daggers and how do they block in place?

I am surprised that you boat’s bow wake is flared out which seem to indicated you are going fast than hull speed? So what is the max speed? The Eagle can reach 10 kts but we are pushing a lot of water as shown in the avatar picture.

We don't know our maximum speed for two reasons :
we never push the throttles more than 2300 rpm (and just for few minutes!) for come closer to our friend and his GB50 for make the photo , you can see on the avatar.
Around 11,4 knts at this moment and if our wake flared out like that it is may be our friend waiting the right moment for the photo, the weather forecast said 25 knts wind, may be it help a little but we have no wind indicator and this day we could just "feeling" and we 'feel' less than 25 kts.(and my stomac also and it is a very good specialist for "appreciate" the real weather
and the second raison , we fill something is "wrong" whit our prpellers , we feel they don't 'eat' enought hp they are 4 blades 27'X27', but
The dagger boards are betwen the section 16 and 18 (on the side of the wheelhouse)you can see them on the photo at
Dérives - Le blog de long-cours
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Old 04-27-2012, 11:07 AM   #150
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Originally Posted by longcours62 View Post
We don't know our maximum speed for two reasons :
we never push the throttles more than 2300 rpm (and just for few minutes!) for come closer to our friend and his GB50 for make the photo , you can see on the avatar.
Around 11,4 knts at this moment and if our wake flared out like that it is may be our friend waiting the right moment for the photo, the weather forecast said 25 knts wind, may be it help a little but we have no wind indicator and this day we could just "feeling" and we 'feel' less than 25 kts.(and my stomac also and it is a very good specialist for "appreciate" the real weather
and the second raison , we fill something is "wrong" whit our prpellers , we feel they don't 'eat' enought hp they are 4 blades 27'X27', but
The dagger boards are betwen the section 16 and 18 (on the side of the wheelhouse)you can see them on the photo at
Dérives - Le blog de long-cours

I see them on the deck right behind the door? So how do you let them down and block in place? How far down do they go? Can you adjust them for different depths? Do you notice much difference with them down?

Thanks for the Picture
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Old 04-28-2012, 04:02 AM   #151
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For lift

the dagger board we just use rope and blocks , they going down just by her weight and block , them ...one day I will finish that with"big screw" sorry i don't know the right worb .
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Old 04-28-2012, 11:00 AM   #152
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the dagger board we just use rope and blocks , they going down just by her weight and block , them ...one day I will finish that with"big screw" sorry i don't know the right worb .

So do they fit in a slot inside the hull? Our sailing dink has a center board the fits into a slot that be taken up/out.
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Old 04-28-2012, 11:20 AM   #153
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We don't know our maximum speed for two reasons :
we never push the throttles more than 2300 rpm (and just for few minutes!) for come closer to our friend and his GB50 for make the photo , you can see on the avatar.
Around 11,4 knts at this moment and if our wake flared out like that it is may be our friend waiting the right moment for the photo, the weather forecast said 25 knts wind, may be it help a little but we have no wind indicator and this day we could just "feeling" and we 'feel' less than 25 kts.(and my stomac also and it is a very good specialist for "appreciate" the real weather
and the second raison , we fill something is "wrong" whit our prpellers , we feel they don't 'eat' enought hp they are 4 blades 27'X27', but
The dagger boards are betwen the section 16 and 18 (on the side of the wheelhouse)you can see them on the photo at
Dérives - Le blog de long-cours
If the props slip you could have them cupped which will grap the water better. On the run about for sking use a 19 pitch with a cup for getting a 200+ lb up out of the water.
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Old 04-28-2012, 01:51 PM   #154
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Yes they pass

in a slot .
And the draft of the boards are around 6 '
As you wrotte before : put 2' more on the boards
put a bigger mast (one friend have a 17 m available) and some more ballast around 8/9000 lbs and we got a motor motor sailor a 60/40
And down wind even a box cross an Ocean
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Old 04-28-2012, 01:59 PM   #155
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For the propeller

we already ask to the maker and two another factory....and after 16 months we still waiting answer
May be put our 27'X27' to 29'X27' (i don't remember if the diam is the first or the second...is the fault of Aloïs !?
You understant what I mean, keep the diam and put more 'angle'
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Old 04-28-2012, 02:22 PM   #156
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First number is the diameter ( diameter X pitch)
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Old 04-28-2012, 09:40 PM   #157
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in a slot .
And the draft of the boards are around 6 '
As you wrotte before : put 2' more on the boards
put a bigger mast (one friend have a 17 m available) and some more ballast around 8/9000 lbs and we got a motor motor sailor a 60/40
And down wind even a box cross an Ocean
Sails were added to sister 58ft. The added blast and twin keels. The sails where added to assist and increase the range. If only if i had an extra 30+ grand.
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Old 08-20-2013, 01:30 AM   #158
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Tom Fexas's viewpoint on semi-planning, semi-displacement

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*From your photos I would agree although the bottom of your boat has more curved sections than the typical semi-planing hull used on something like a GB, CHB, etc.

To me a displacement hull is one that, while it can be forced a bit faster through the water with the application of a huge amount of power, most of that engergy is absorbed by the hull digging a deeper hole in the water.

A semi-planing hull (I agree with naval architects like Tom Fexas that semi-displacement is simply a marketing term) is one in which an addition of a lot of power results not in the boat digging a deeper hole but in generating enough hydrodynamic pressure against the flatter surfaces of the hull to begin to lift it up in the water, thus reducing wetted surface, thus reducing drag, thus enabling it to go faster albeit with an increase in fuel burn--- very possibly a significant increase as in the case of the previous generation of GB hulls.

A planing hull is just that.* A hull that is designed to generate the maximum possible hydrodynamic force against the wetted surfaces of the hull and thus lift the hull a lot and reduce the drag a lot in as efficient a manner as possible.* This in turn means the boat can go considerably faster than a semi-planing boat with the same power and WAY faster than a displacement boat of the same length, and the greater speed makes the increased fuel burn at least theoretically a good return on the investment.

Those are my definitions of the three hull types.* So based on them, I would say Coot has a semi-planing hull but a pretty inefficient one if one actually wanted to take advantage of its ability to be lifted and reduce the wetted surface and drag.* Major power would be needed.*

So why use a semi-planing hull on a low-powered boat like the Coot or an early GB?** One advantage of this hull type even at slow speeds is that the flat after-section, sharp-chined hull will provide a less rolly ride than a hull with a typical, rounded displacement configuration.* This is certainly true of our GB.* However, less roll comes with a price in that the characteristics of the roll with its sharper "snap back" are uncomfortable to a lot of people.

The second advantage is that a semi-planing hull can be driven a little bit faster than displacement speed with the application of not-that-much-more power.* So while the displacement speed of our hull is seven-point-something knots, the hull can be driven at eight, eight and a half knots without a lot more power or fuel burn needed.* A half to a whole knot more speed doesn't sound like much but to a lot of people--- and the sales department--- it is.

The hull on our boat could be driven at 14 knots or so.* Later GB36s with big engines can achieve this.* But at that point the fuel burn becomes enormous.
Excellent posting. I always did like some of Tom Fexas's designs. He was somewhat a rebel as well.

Now that you brought it up, I remember reading his 'definition' of planning, and semi-planning.
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Old 08-20-2013, 01:39 AM   #159
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I'm just now reading thru this subject thread....

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I think semi-displacement is a totally bogus term thought up by marketing people who wanted to associate their boats with the supposed ruggedness, seaworthiness, etc. that "displacement" conjures up. Same marketing mentality that applied the term "trawler" to what in reality is a cabin cruiser.

Displacement is like dead. You either are or you aren't. You can't be semi-dead, nor can a hull be semi-displacement.
Laughed my a.. off
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Old 08-20-2013, 01:44 AM   #160
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*I'm sure Eric would like to chime-in here and be counted among the full-displacement group, but I sense that his conservative views with regard to HP and hull design may be only to mask Willy's true capabilities.
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Add on the wing sail and you should be ready to make a bid for the America's Cup
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