Build Down verses skag boat

[guitarman]

What are the differences between a build down and a skeg boat? and under what situations would one be better that the other?

 

[tomy]

hi guitar, I know that there was a good explaniation on this site once. with pics. I quickly checked the "search" but don't have time today. did you search this site?

 

[F/V First Team]

Built down Skeg Built

See the difference in the turn of the bilge of both models? Basically when the plug is created the built down method planks right from the shear, to the turn of the bilge, and onto the keel in fluid arcs.
A skeg built boat is planked from the shear to the turn of the bilge and centerline. Then a square series of stacked planks are put on the centerline to create the keel area.

Skeg built boats are easier to build plugs for, and are the old way of building a wooden boat because the keel can just be solid hewn timbers with a few holes drilled in them and along the length for the shaft.

Supposedly skeg built boats are "faster" but I don't believe it for a second. Plus they tend to pound the fillings right out of your teeth since they ride up the wave then come crashing down, with the advancing water slicing right up along the keel then ramming full force into the bottom of the hull. On the built down the water starts being diverted from the subtle slant of the keel, hits that reverse curve and slides up alongside the hull giving a much softer ride (your wife won't be bitching about being thrown around like a rag doll) so you have a much better boating experience.

An added benefit to built downs are that you get MUCH more room under the deck. The engine can be slid further down into the boat, giving more positive ballast and you can fit more goodies down there. Maybe instead of a 20 gallon water tank you can have 40, instead of 200 gallons of fuel you now can have 400, you might not consider the space below deck because you don't spend much time there but it is a godsend if you ever have to be down in there because something went wrong. No one likes to play bilge rat, and a stuck bilge rat is one unhappy fellow.

True story: Myself and another were heading to a race in somewhat turbulent weather, seas were in the 2-4 range and the wind was howling just a wee bit (sustained 20's) I in my NB36 and he in his CB 34, both have the same power - 410 Sisu and both with comparable speeds. Both of us cruise at 25 mph but only one of us was able to do it that day, because the terrible pounding made them slack back to around 17-18, and even at that reduced speed it was still bouncing at a fairly good clip. Up ahead the nose was just raising and lowering with the roll of the waves, no jostling, no banging, just a sweet soft ride.

Later on that day when I decided to continue East while the rest of the fleet tucked tail and ran back West, I found myself in increasingly worse weather with seas creeping up steadily around the 10 foot mark, winds now pounding the side curtains at 30 mph I too did have to throttle back quite a bit. But not due to any adverse effects of pounding, rather I was running with the waves but I was going much faster than they were and the six year old, on her first real big boating adventure, wasn't too keen on the pitch poling sensation of cresting the wave and plunging down the other side. Throttled back and it was surfing from there, only jostling was from the random rogue wave that bashed against the transom and rained down a bit of salty sunshine upon us.

I can't comment on the ride of a skeg built boat in those conditions because no one wanted to come and play, so we have no data. It was an awesome trip and I'd do it again in a heart beat. Only this time I would check my propeller and take the damn rope out!

 

[Frank Grimes]

Should open up a lively discussion....I know there are some skeg proponents on here.....

 

[Powderpro]

Should open up a lively discussion....I know there are some skeg proponents on here.....

Skeg boats are so fast, they tend to skip across the tops of the waves .

Here's a picture of one of the finest DE hull in existence, it's a pic I took of a 38' Flowers- it's built down. Notice the smooth curve where the keel transitions into the bottom of the hull. NICE.

 

[Powderpro]

1st pic is my 34' Calvin Beal. Notice the bottom of the hull meets the keel with a hard angle. 2nd pic is "Moxie", a 36' Flowers (same hull as the 38' Flowers). It's obvious to see which hull is going to deliver a softer ride going 20 knots through chop. Each hull design has its purpose and I don't think either one is better than the other- it's up to the user/owner to determine which design is better for their use.

 

[TwoRivers]

Is this BHM builtdown ? Not very good pictures .
Thanks

 

[MDI45]

TwoRivers,The BHM is built down.....My 45 MDI is also built down in picture one and pic two is my old 36 Wayne Beal which is skeg built

 

[GLA]

bhm is definately a built down hull. I had a chance to look at a 39 below decks
seemed to have 3-1/2 ft under the deck, just behind the house

also had a 650 mtu under the deck and held 800 gallons.

one consideration with a fully built down hull is roll, with a beam sea the keel really walks over when a swell comes under the boat. not so much with a skeg boat

 

[TwoRivers]

Thanks guys. A learning process with a downeast boat in the South ! Nothing but bass boats and party barges around here !

 

[greg]

Here are some pics of my jason 35. Definitely a candidate for keel walker though I don't have the ponies to find out. Dunno which it is tho.

 

[MASTERENEGADE]

Im gonna say skeg built. Altough i could see in some angles where it could go built down. Either nice boat.

 

[Captlvb]

Travis

The NB 36 is on my short list as I have fished on a charter boat ou tof Green Harbor a few times but the weather was always nice. How does your boat drift in heavier seas?

Lou

 

[F/V First Team]

Travis

The NB 36 is on my short list as I have fished on a charter boat ou tof Green Harbor a few times but the weather was always nice. How does your boat drift in heavier seas?

Lou

does pretty good while out hauling gear, i don't really find myself drifting.

 

[googinhater]

Travis

The NB 36 is on my short list as I have fished on a charter boat ou tof Green Harbor a few times but the weather was always nice. How does your boat drift in heavier seas?

Lou

I did some harpooning on the Lilly out of glo and she is a tank even with the tower on her great boat the 36-38 are both on my list fished the gray ghost a 38 loved it also a tank

 

[John Riddle]

The terms built-down and skeg-built originated to describe the techniques utilized in forming the hull’s transition to the keel in traditional wooden lobster boat construction. The shape of a built-down hull exhibits a pronounced S-curve as it transitions from the bottom of the hull to the keel. The planking is fitted to that S-curve and forms the deep bilge commonly seen aft of the engine (see sketch). By contrast, the shape of a skeg-built hull does not include a pronounced S-curve, resulting in a shallower, flatter hull section but with an added skeg. The skeg is basically a slab of wood, generally built up of several stacked pieces that is fastened to the structural keel. It’s a faster and easier shape to frame and to plank which I have seen explained as a primary reason for its development.

Molded fiberglass construction has now blurred what used to be the clear difference between built-down and skeg-built shapes. An effort to blend the best features of each in a favorable way has resulted in a variety of hybrids that are a cross between built-down and skeg-built, although some designs are more heavily skewed toward one or the other. That indistinct difference has led to a number of questions and discussions defining those shapes and their attributes on this forum and others.

By itself, the difference between a built-down or skeg-built shape has little to do with the performance or handling characteristics of a given hull, except that if everything else is equal (which it isn’t), a skeg-built hull will tend to be somewhat faster. Waterline beam, deadrise, displacement, the firmness at the turn of the bilge and other factors have more to do with performance and handling than does the cross-section at the keel. It makes for interesting discussion though!

 

[F/V First Team]

Jason 35 is a skeg built

 

[guitarman]

Wow this is great stuff thanks for all the info. So on a 28' foot boat if you have a built down you could get away from the motor box in the cabin, am i understanding that correctlly but with a shag boat you would need the motor box is that right?

 

[F/V First Team]

If it was a built down 28 you would have more room to possibly slide the engine completely under the floor without needing an engine box/step up platform than you would with a similarly sized skeg built boat, yes

 

[guitarman]

so does that mean then that any boat in has the engine box is a skeg boat?