Reverse bow / inverted bow: thoughts and questions

I've merged this thread with one of our previous reverse bow / axe bow threads.

Feadship Predator was originally going to use a standard stem (raked back in towards the hull), but the speed it was wanting to achieve it made more sence (better hydrodynamics) to have an axe bow (it did have 23000+hp), and the tank testing prooved it. they also put the massive wave braker on the fwd deck for if it was getting a few waves over the bow... plus the reverse sheer doesnt help its argument. so i have read.

but u can design a hull with the fwd rake stem that wont pitch pole, u just have to know where to put the extra volume, imo. the youtube vid was a great example, the fwd raked boat had less wave resistance then the other boat, had the right volume and flare and directed the water better than the other, and thus mad it look to easy. the other boat was pushing to much water creating a whole for the bow to sink into, and thus slowing it down.

the wave piercing catamaran are not to good for the heavy seas i have found out first hand time and time again (Tangalooma Express).

and to answer the question, i love the fwd raked bows, just as long as u get the superstructure design right and it all complements eachother. that first drawing is unreal! but time and place.

far

Sorry, was up late last night and just woke up. Did they change the definition of rake while I was sleeping?

I'll join Marmot in being confused by this statement... The forward raked bow has less resistance and made it look too easy?

Let's clarify - Green hull, or red hull?

Nothing new?

I was leafing through my books on ships and noticed reverse bows starting in the 1860s. The Konig Wilhelm of 1869 being an early example. Google SMS Konig Wilhelm produces a nice flicker photo. The design seems fairly popular for both war and merchant ships all the way to 1915. Google SMS Konig and open the Wikipedia article for a hull (1914) that looks quite a lot like what we are now talking about. Suddenly it seems, in the early 1920s the design is abandoned. By everybody. Anyone know why?

haha! my bad... big day and night before that post. the 'green' boat has a better entry than 'red' boat. imo

also a vid of Feadship Predator.

http://www.youtube.com/watch?v=sLJupLy1Nrc

far

I wasn't around to listen to they guys who made the decision but one reason warships stopped using it was that ramming was no longer high on the list of tactics for the fore and aft hat crowd.

I don't think there were many merchant ships designed with a reverse rake bow, plenty of bluff bows, but a reverse rake makes for a wet deck and and really reduces volume for cargo. Speed and power was increasing rapidly in those days as well as ship size and most hulls were by then rectangular sectioned as far forward as possible for capacity and a forward rake flared bow was bouyant and dry and had room for bosun's stores and machinery as well as forepeak ballast.

If you look at the hull shape of the Bourbon X-bow ships, they have large volume forward and low, reminiscent of the old "apple bow" style of the 18th century ships, before the tumblehhome and reverse rake begins. This was difficult to build in iron at the turn of the century and reduced cargo volume as well.

Fashion has a lot to do with it as well. In the 1970's the Indian merchant marine had bunch of ships that didn't have a curved plate on them. They were cheap to build, didn't waste useful volume, and worked, but they looked funny and the next generation was all curvy and smooth again.

Thanks

Function or Fad?

After reading Carl's report and seeing more axe bows are coming. Is this design being exploited by designers, "Fad", or has it been determined this type of bow is superior to traditional bow designs?

Yesterday's style has always been a fad because it didn't last through today. As for superior, that's a relative term. Are you talking about below deck volume, on deck volume, dry foredeck, smooth ride, sea keeping in a beam sea, speed, fuel economy, etc.? It all depends on the fad of the moment.

What I mean by superior is; better sea keeping, fuel economy, speed and stability. Sailboats have been using this bow design for many years and the axe bow was used in powerboats decades ago.

I guess my definition of a fad is will the owner wake up in five years and say "what was I thinking". Outside of that, what is a fad is mostly determined by the test of time ie: disco (which I still like ) and interested public acceptance - yachting community. My view maybe a little biased since I am not a fan of the axe bow used on powerboats.

Well said NYCapt. Different strokes for different folks. Each design has merit and both are here to stay.

Well, that seems to happen to most boatowners about every 3 years today.

(Grateful Dead, Muddy Waters, Boxcar Willie)

I guess that would make you a traditionalist since the Eurpoean look has been popular for the past 20 years, and the SF flare for 40. Unfortunately, those that are trying to expand on that in new directions today can only seem to come up with raking the windshields back to rediculous levels (unless you enjoy baking in the sun and seing nothing but your dashboard at night). Maybe because I'm old I like the forward raked windshields that are functional and look forward to new designs (which will probably draw on designs from 50 years ago ). The next fad.

I think in the larger superyachts it's coming back because of it's hydrodynamic performance... long story short, the boat should use less fuel.

But with the small designs, say anything under 70', it's becoming a bit of a fad. There's not many boats out there with this design feature... so it makes for a good selling point... (imo) I think there's more cons then there are pros for boats in this size range with this design feature (Marmot stated a few), and new comer designers might need to rethink there ideas.

Far

May I ask if you mean 70 feet or meters please?

'= feet