Alaska fishing hull

Discussion in 'Boat Design' started by coldwaterak, Nov 26, 2011.

  1. gonzo
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    gonzo Senior Member

    Where is the propeller opening? Most trawlers have a reverse curve or partial tunnel to tuck it in. It seems that it would protrude too much with the danger of snagging the fishing gear. I think that a single chine would offer better stability and less resistance.
     
  2. viking north
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    viking north VINLAND

    God I hate that combinstion of reverse slope on the windshield and an overhanging eyebrow. Thats just an inward sloping V to trap oncoming green water when she burys her nose. That V shape formed between the winshield and the eyebrow will increase impact loads on the winshield expodentially. I know they all use it but in my book it should be outlawed.(I'm going to get flak for this I know) While still not a good design a straight vertical wrap around sectional windshield is much much better to take green water in that it deflects rather than traps tons of oncoming sea. If you feel you just got to have this suicide design at least make use of some sort of spring loaded eyebrow that will hinge up and back to relieve the pressure and get the angles 150% correct on that deflection lip around the forward bow, better yet it might not hurt to put a reverse curve lip along it's upper edge. Once again I know I'm going to catch hell for this opinion but i've been there and it's not a good situation when the windsheild ends up on the wheelhouse floor.
    P.S.While in the shop working on my keel I had second sober thought on that reverse lip idea(never admitted to being a designer ;), It could actually cause more problems in tripping a boarding sea downward which is the desireable opposite. I just hate those reverse sloping windshields no matter how they try to overcome their faults.
     
  3. gonzo
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    gonzo Senior Member

    Reverse windshields are there to comply with the law. You are required to have clear visibility of the foredeck. The eyebrow is not necessary and I agree that it creates extra stress when you ship water.
     
  4. viking north
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    viking north VINLAND

    Can't argue with reverse slope giving good fore deck visibility but never knew it was the law-Learn something new every day. Wonder if they have the option of a vertical (90) deg. also as it would also give excellent deck visibility. Then again unless it was a rounded configuration a 90 deg. impact would possible be worst than the angular deflection of the reverse slope. Looking at the design again the windshield looks protected as much as possible while still having forward visibility out over that bow--So like all boat design we're back to attempting a balance between function/form and hopefully safety--
     
  5. gonzo
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    gonzo Senior Member

    It can be any design as long as it gives the visibility required.
     
  6. dsharp
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    dsharp Junior Member

  7. fastwave
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    fastwave Senior Member

    A lot of people have commented on the bow. I would like to high light a concern on the stern. The stern is very flat, and some ships do suffer from severe stern slamming in heavy seas.
    This depends a lot on the vessel and conditions. This vessels seems relative shirt compared to the beam so might no raise the stern high enough for this to be a problem. If it does though, then the stern sections are too flat.
    This is something for u to consider.

    Generally a prosimising design. Good Luck
     
  8. coldwaterak
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    Location: Alaska

    coldwaterak Junior Member

    Regarding the windshield/fore windows.... Definitely something to consider. I've been standing there looking at the green water pressing up around the house. In fact as a teenager, I was on a boat that cracked around the deck line of the house from exactly what you mentioned.... the bunks were always damp after that :D

    I've notice alot of the newer designs out there still go with the forward sloped windows but have done away with the visors:

    http://www.seawork.com/__data/assets/image/0005/430790/South_Boats.jpg

    http://www.kvichak.com/boats/pilot_big2.jpg

    I think it looks sharp not to mention having windows above on the ceiling brings in some great ambient light...
     
  9. coldwaterak
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    coldwaterak Junior Member

    I've already rounded the stern some more. The only reason I am hesitant to take too much more out of the corners/stern is that it will start cutting into the deck space/fuel tank voids.

    Obviously the squat wide format of these hulls treads on a fine line of having boats that breach horribly in following seas. I'll post the model in a pdf again here shortly and you can tell me what you think.

    Also i've lightened up the angle of the chine, especially forward.... let me know what you think.
     

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  10. viking north
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    viking north VINLAND

    The reduction in the chine ridge in the forward section will definately go along way in causing a deflection rather than impact of the ice as there is much less for it to get hung up on. On your opening post you refer to a site showing The Vessel Saint Paul, if you look carefully the very top section of the bow is flared outward- I have a feeling this is also a design feature to deflect some of the oncoming sea helping prevent impact with the windshield. Also on the second site you refered to, post 23 if you look carefully one of the craft has a deflection V shaped structure on the fore deck(looks like red gas cans behind it). Sometime back on another thread a poster mentioned this also was a design to help prevent green water impacting the windshiel. It's definately a concern I would take all precautions against. I am not a designer but have experienced a sea taking out a forward sloped windshield and have been gun shy about it every since so it might just be i'm overconcerned about it. If it were my craft and again i stress I am not qualified to be giving any recommendations here,I would definately consider a rounded vertical windshield design having multiple smaller glass panels.
     
  11. Joe Petrich
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    Joe Petrich Designer

    Sponsoning a boat does not necesarily result in a good hull form afterward. If you will be building a new boat you should consider a clean sheet design or one of the many wide body seiner designs already drawn up. Single or double chine as Ad Hoc said. Fwd bulwark looks like it will hold a lot of water when you dip it and the main deck bulwark looks a bit high as well. Generous freeing ports will be required. I might minimize or eliminate the focsl deck bulwark so water clears faster and then strengthen the pilothouse.
     
  12. Joe Petrich
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    Joe Petrich Designer

    Forward sloping windshields are not the law. They are there to minimize reflections from the wheelhouse on the glass. Just about every fishing vessel in AK has fwd sloping windows and a brow, and few if any lose their brows in rough weather. The fwd slope also allows for some electronics to be housed in the overhead, and keeps the windows a bit drier in the rain.
     
  13. Joe Petrich
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    Joe Petrich Designer

    That forefoot will catch in a heavy following seas and will contribute greatly to broaching in those conditions.
     
  14. viking north
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    viking north VINLAND

    If that be the case maybe we should also put them in our vehicles. I am not convinced they are necessary as much as they have become an accepted style, however I can agree they do give a better view of the deck directly under the wheelhouse, and even at that is the trade off over a rounded vertical design worth it. Electronics overhead ??? Nothing more than what can be achieved with a vertical or slightly aft sloped set up. Mark my words this design will go out of favour with fishermen in rough water fishing areas and there isn't a fisherman out there that has, as, one of his greatest fears when he's caught facing monster seas more than, an imploding windshield. Sorry but I just don't like them. No disrespect but from this old builder and fisherman,the best i can offer is to agree to disagree and you smart, well educated, qualified designers need to come up with a better system, I.E. a windshield composite that is back sloping, anti reflective, and has a reverse face on it's lower area that gives a clear view of the deck below. Something similar to that in a modern excavator or high rise crane. ---Geo.
     

  15. Joe Petrich
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    Joe Petrich Designer

    Well, I must respectfully disagree with you. Thousands of Alaska/Bering Sea fishboats stand as evidence that fwd sloping windshields work, and work quite well, including the ones we have designed and built.
     
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