Reverse bow / inverted bow: thoughts and questions

Could this model be a Med special? Not really intended for big swell?

Eric's points on buoyancy are right on the money, of course. But to some degree couldn't this concern be applied to all of the "wave piercer" family?

Kelly Cook

Never been to the Med Kelly?

Ooof! Got me Lars. Only wish I had been to the Med. So is typical Med swell is the same as the Atlantic?

Kelly

A little less, but 8-9 meter waves are common in storms and up to 25 m (80 feet) has been measured. I think a large cruise ship was hit by such a wave a couple of years ago and lost all controls when the bridge windows broke...

This was between Corsica and Mallorca, where the Mistral winds can be pretty naughty.

Yikes !

This was my Coventry University Final Project. Indeed the initial idea for the reverse bow was a styling element but this 50m yacht was designed to be fast so her bow would raise at speed. The previous thread was correct however in saying that youd be drowned if standing on the forward deck area when in motion.

Eric, I agree with you on the wavepiercer bow.
However, volume above the waterline does not necessarily equal seakindliness. I recently made a short trip on an Axe-bow ship and saw video footage of tank testing comparing a conventionally bowed ship, an axe bow and a wavepiercer in heavy seas.
The wavepiercer acted as you say, but the axe-bow behaved a lot better at high speeds in heavy seas (and was still going fine when the others were basically sinking). It had a dry ride while it has little or no reserve buoyancy in the bow.
But, there's a lot more to the axe-bow concept than a vertical stemline and high freeboard at the bow. Including some compromises most yacht-owners would not like to make.

Best regards,

Bruno

Reverse Bow

In my opinion, the style of a reverse bow is worth any mild drawbacks in handling. This is what i drew up this afternoon; forgive my art skills, please.

Give me a good old 45 degree (fwd raking) stem anyday. I'd rake it even more if the interior package vs overall length would let me.
Got bored, so I worked out that for a (powered / planing) hull designed to be largest possible just under the 24m Load Line Length rule, I can have a hull around 27 metres long stem to transom if the stem is raked around 45 degrees. If the stem is vertical, the hull cant be longer than 25m from stem to transom. Around 6 feet less deck length, designed under the same rule.

Inverted bow, thoughts and questions

After having read the positive comments of the captain of the new Feadship Predator I am wondering. Does the inverted bow concept work with other styles and lengths or is each design a "one off" that was must be carefully calculated.

And then, what about....
Cost of design and construction
materials limitations, Steel, composite
are we likely to see more designs like this
and whatever else I didn't think of or know about....

I am mainly wondering how adaptable this concept is, as well
as any downside.

Your Thoughts,

While waiting for comments, here are links to some existing threads -

http://www.yachtforums.com/forums/general-yachting-discussion/3856-new-bow-configuration.html

http://www.yachtforums.com/forums/yacht-designers-discussion/6361-reverse-bows.html

http://www.yachtforums.com/forums/technical-discussion/6671-axe-bow-enlarged-ship-study.html

Kelly Cook

Some preliminary comments of the captain were posted, but have the sea trials results for Predator ever come to light? Any published reviews of the boat? How do the captain and crew find her now that they've lived with her for a bit, and presumably encountered some inclement weather?

I've looked for the sea trial results for Predator but haven't found anything yet. My background is in land based architecture and space planning.... trying to learn more about hull design and others aspects of building on the water...

as to my understanding the down side of this type of hull design is that you need to have a certain length in order to have an affective performance and there is a lot of compromise in terms of space due to very limited beam at the fore part.

furthermore, at anchor one can have problems while swinging from side to side, as the chain may easily get cought in the bow.

Thanks, just the kind of thing I would have no idea about. It was suggested in some of the other threads that the inverted bow might be appropriate for trawler or expedition style vessels. What's your take and do you know if there are any built this way. The only thing I've seen is the very large Orca X bow...

Hi,

That is not surprising.

There will be a certain amount of sea trial data onboard the yacht but the majority will be held by the shipyard. I seriously doubt they would release it for general consumption.

I do not know of any of the premium builders who do release the whole lot.

I do not have enough technical knowledge to comment; however I know that there are certain commercial applications especially for supply vessels for rigs in the rough coonditions of North Sea and there are attempts to have some cargo and container vessels with this axe bow designs.

Like these, for example: http://www.youtube.com/watch?v=Mqcpe5au_7M

There's a fairly remarkable difference between the two bow types.