Would a Bulbous Bow be Legal in Rowing?

[crewu]

Bulbous bows are used on cruise ships, container ships and numerous other types of vessels and are adopted to create huge fuel efficiencies as well as increase boat speed by creating a wave ahead of the ship that I guess reduces drag.

Has 1.) anyone ever tried putting one on a shell and 2.) would they even be legal in rowing?

If you don't know what I am referring to just google 'bulbous bow' and look at the images. They have been around for decades but I have never heard of them come up in shell design conversations. Pretty interesting stuff.

[JFrancis]

Seems like a shell wouldn't be go fast enough to make use of a bulbous bow. If it could, it would certainly add cost to the hulls.

[Coxswain3]

I'm not sure how practical it would be to have a shell with a bulbous bow:

1) Because rowing shells don't move at a constant speed/fast enough
2) I feel like a bulbous bow would trap lots of debris and greatly increase what would otherwise be a minor encounter with a small log into a gaping hole in the shell by trapping it instead of letting it slide under the shell

[southernrower]

I am not a naval architect but I think that the bulbous bow is efficient with deep V hulls. In terms of laminar flow(is that the right term?), I think the design of rowing hulls creates the same/similar bow wave that the bulbous bow does for deep V hulls.

[KitD]

It's been discussed a few times here. Search for "bulbous bow".

ISTR they don't really work for racing shells due to the hull length and variable speed through the water.

[crewu]

View profile
More options Jan 9 2004, 2:17 am
Trurl <tr...@cyberiad.net> wrote in message
> The program "Michlet" (available from http://www.cyberiad.net/michlet.htm)
> can calculate wave resistance, viscous drag and wave patterns, and is
> particulary well-suited to thin hulls like rowing shells, kayaks etc.
> Leo


Hi Leo
Nice to see you're still lurking here!
There is a boatbuilder here in Perth named Ken Edwards who has built some
experimental bulb-bow singles, which I've seen in his shed. He has told me
they are very fast. Can't tell you any more than this right now.
Nick

The above was from the Rec Sports Site KitD. But apparently a Perth (Scotland?) made "very fast" single in 2004 with a bulbous bow has not been heard of since.

[KitD]

That would be Australian Perth. Nick was an RSR regular from there a few years back.

This post from Bill Platt is interesting. He was a naval architect who frequented the board for a while. Interesting guy.

https://groups.google.com/group/rec.spo ... 1354?hl=en

[sul]

That would be Australian Perth. Nick was an RSR regular from there a few years back.

This post from Bill Platt is interesting. He was a naval architect who frequented the board for a while. Interesting guy.

https://groups.google.com/group/rec.spo ... 1354?hl=en

Had dinner w/ Nick late last fall when he came thru NorCal.

send private msg to me if you want to contact him.

[DudleyP]

Ken Edwards is in Perth Australia. He designed and builds the Edon recreational sculls see this website

http://www.virginiarowing.com


I've not heard about the bulbous bow boats though so maybe he never put that design into production.

Dudley

[JD]

Let us be sure we are answering the question. Would a Bulbous Bow be Legal in Rowing?
USRA rules state:
ARTICLE III - EQUIPMENT
Part A - Construction and Design
3-101 Free Construction of Equipment (*)
Except as specifically limited in these Rules, there shall be no
limitations on the design and construction of boats, oars, and
other equipment.

Rules do not go on to talk about mono hulls, shapes,or bulbous bows.
So, yes, it would be legal.

[crewu]

3-107 Foreign Substances
No substance or structures (including riblets) capable of modi-
fying the natural properties of water or the boundary layer of
the hull/water interface shall be used during a race.

JD I was thinking the bulbous bow might be interpreted as a "structure" in this case...what do you think?

[JD]

Huh. I wonder if the "changing the natural properties of water" part would apply.

Modern catamaran design (long, narrow, high-speed displacement hulls) is trending toward a "wave piercing" bow. And here is a military design which is both wave piercing and bulbous.

[KitD]

3-107 Foreign Substances
No substance or structures (including riblets) capable of modi-
fying the natural properties of water or the boundary layer of
the hull/water interface shall be used during a race.

JD I was thinking the bulbous bow might be interpreted as a "structure" in this case...what do you think?

I don't think a bulb affects the boundary layer at all, and certainly not the natural properties. The structures being referred to there are the minute "shark-skin" riblets that racing yachts had for a time that do affect the boundary layer.

A bulb is intended to reduce wave drag AIUI.

[crewu]

So, let's say someone makes a shell with a bulbous bow and gives it to a very decent couple of oarsmen who have entered to race the US Men's 2- Olympic Trial. At this point we have no clue if the bulb works or not but safe to say it is not slow as these hypothetically respected oarsmen have decided to use it.

Who actually makes the determination as to whether the shell is legal or not? Is it the same referee who weighs the shell?

I recall when the first all carbon fiber bike was first introduced at the Olympics it was a pretty average British rider who won the gold medal on it. How would it all go down for a national team trial here? Since we know the bulbous bow adds massive fuel efficiencies on many types of vessels, what if it actually did work on a racing shell and left its crew fresher for the last 500 meters?

[JD]

So, marine architects are starting to use bulbous bows on cruising yachts, going 10 knots. If the thing remains underwater, as in the reverse-shaped wave piercer in previous picture, why wouldn't it work for 8's at the speeds they go? Could it reduce porpoising and wave drag?