Fishing Vessel Stern Bulb

Hi Guys ¡¡¡
Recently I was asked to give an opinion on fishing vessel stern bulb as the PDF picture is showing.
Can somebody help me giving me information where I can find papers about this matter ?.
Can somebody give me his personal opinion ?
Any guy with experience on this ?
I will appreciate very much any reply about this issue.

MVD535

 

Doesn't look like a 'bulb' to me - merely an 'overhang' to give clear passage when hauling nets on drifters, trawlers and ring-netters etc. It avoids tangling your fishing gear with the prop, and is standard design for blue water fishing boats - certainly if built in Britain.
As to information I can only suggest contacting any of the builders still building 'heavy' trawlers in Europe. (A dying breed I'm afraid.) Or get in touch with any of the fishing journals (not angling - but fishing).

 

I think the state of the art in large ship-building is just starting to accept stern bulbs for reduction of stern wake and increased efficiency. I doubt that it is something that has been thoroughly researched, if at all, for small craft.

~ ALowell

 

Just thinking out loud here...
There would - quite obviously - be an increase in the displaced volume aft, but also in the wetted surface area. Whether you'd get the same thing, with less penalty by simply increasing the hull's volume aft, could probably only be determined by the modelling...
There would be some improvements, I guess, in terms of heave (pitching) in the same way as with a bow bulb, but surely not as effectively as the shape isn't optimised for this.
Then there's the interuption of flow to the prop....

 

Something about stern bulbs in papers:
http://books.nap.edu/booksearch.php...1&Search This Book.x=11&Search This Book.y=15
http://books.nap.edu/booksearch.php...359&Search This Book.x=0&Search This Book.y=0
http://books.nap.edu/booksearch.php...1&Search This Book.x=17&Search This Book.y=12

Something else:
http://www.springerlink.com/content/f59e6w6pfw5hmquk/
http://www.springerlink.com/content/6f68q6uupbcxgple/
http://www.searchpdf.com/studies/marsim2000/pdf300/041.pdf
http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADP003803
http://www.nmri.go.jp/spd/spd_report/SPD_SPM.pdf
http://www.tsuneishi.co.jp/tess/factbook.html


Cheers