How much Horse Power do you think this needs?????

Discussion in 'Boat Design' started by Ravencry, Mar 29, 2009.

  1. Ravencry
    Joined: Mar 2009
    Posts: 19
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Iquitos

    Ravencry Junior Member

    10---speed-boat.jpg
    Here is a fugimori that has a big motor on the back, there is to much spray to see how many horse power is there but I am sure it is a lot.
    I can get a Fugimori used for around $1000. But I am not sure that it would be worth it. If I got my own make using a good design it would probably same me money in the end. Thanks again, Ravencry
     
  2. tom28571
    Joined: Dec 2001
    Posts: 2,469
    Likes: 113, Points: 63, Legacy Rep: 1728
    Location: Oriental, NC

    tom28571 Senior Member

    This would have been great information to have from the start. Loading is not as great as I thought it might be but heavy enough to be serious for a small boat.

    People in dugouts must love to see that Fugimori coming. Looks like fun for about an hour and then not so much fun after that. That wake looks like poor fuel mileage also. Your aluminum boat doesn't sound too bad on either speed or fuel use but can probably be improved on in both respects.
     
  3. Ravencry
    Joined: Mar 2009
    Posts: 19
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Iquitos

    Ravencry Junior Member

    Check the stats on this boat. Let me know what you think. I obviously would not be able to purchase this boat, but it gives me hope. copy and past the web address.

    www.wooldridgeboats.com/brochures/26F_SSPilothouse_PD_Single115EvinrudesWeb.pdf[/url]
     
  4. tom28571
    Joined: Dec 2001
    Posts: 2,469
    Likes: 113, Points: 63, Legacy Rep: 1728
    Location: Oriental, NC

    tom28571 Senior Member

    Raven,

    Now you have found someone who knows how to make a boat haul a load at speed on lower power engines. However, notice in the video that in the first part, the trim angle is pretty high and not as high later with the same load. That is because they moved the barrels further forward and when they increased the load, they placed them as far forward as possible. As I said in the beginning, your boat needs a large footprint on the water and this footprint must be of high lift character, meaning pretty flat.

    Moving the weight forward trims the boat down and exposes more bottom area to the supporting water. It's not rocket science but it is important. None of the drawings you offered show enough regard for these ideas. A transom trim tab like that shown on The Good Skiff in my first post would help with boat trim.

    These boats in the larger sizes would be great for your needs. I am not crazy about garveys but on calm rivers they would probably be fine. They are not too wet at speed but will wet the crew at speeds just above displacement speed. That flat forward bottom smacks the water and throws it up so wind can send it into the cockpit. They are drier at higher speed because the boat is gone before the spray can come back on you.
     
  5. baeckmo
    Joined: Jun 2009
    Posts: 1,110
    Likes: 115, Points: 63, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    I am surprized that nowhere in this forum I have seen reference to the TMB series 62 hull shape! In particular, it would be a perfect basis for a boat with your specification. There simply is no other planing hull that has generated so much "planing knowledge" as this one. There is a "library full" of tests in various configurations and with a variety of spray-rails, bottom rise angles and wedges here and there.

    In its basic shape it has a remarkably low resistance and is not too sensitive to mass center variations. In addition, it is from the beginning designed to be built in sheet material, with all surfaces of single curvature. With its rather full bow, it has better behaviour in a following sea than many of the "flashier" hulls, that are prone to broaching violently. This also makes it a good choice for applications powered by water jets, surface propellers or "long-tail" drives, where the thrust line is high, or where you just have a bunch of people up front.

    For someone, who is taking his (her?) first steps into the design/building djungle it is wise to use as much as possible of official, verified know-how. This way, you always have an established benchmark to compare your own achievements with.

    The basic sections plan for the mother model occurs in many textbooks, "Principles of Naval Architecture", edited by John Comstock SNAME, is one example. If you cannot find a suitable reference, mail me back and I will send the plan; I don't think anybody would start arguing about "immaterial rights" here.....!
     
  6. apex1

    apex1 Guest

    This one:
     

    Attached Files:

  7. baeckmo
    Joined: Jun 2009
    Posts: 1,110
    Likes: 115, Points: 63, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    Hi, that's quick enough, and exactly the one. Though maybe the Clement/Blount paper is more directly applicable for Ravencry's job. The parent model, no 4667-1, sized to Lp~8.5 m would carry the load easily. Just have to check static stability with people moving around....

    Personally, I would use the DNV 15 m rule: "Heeling less than 12 degr. with a load corresponding to the max pax number, with surface load 300 kg/m2, displaced as far as possible to the ships side. In this condition, the freeboard shall not be less than 0.2 m anywhere". Better suggestions anyone?
     
  8. Ad Hoc
    Joined: Oct 2008
    Posts: 6,081
    Likes: 346, Points: 83, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

  9. BWD
    Joined: Aug 2006
    Posts: 229
    Likes: 11, Points: 0, Legacy Rep: 128
    Location: Virginia, US

    BWD Senior Member

    I think unless you have free labor and make it of local materials, any boat that size will cost you more than $1000 to build, especially if there is any paid design or labor in it. No? Time to build is an issue also.

    So the fugimori for $1000 sounds the best bet so far.
    It's there.
    It works in the area you will navigate.
    Crew and any local passengers are familiar with it.
    Locals may be more likely to see it as a local boat, not an outsider or as much of a target for theft, (or for mixed feelings).

    I bet a suitable motor to plane it can be had for under $10000. That would leave you >$9000 for fuel, repairs, and supplies to help with your mission(s).

    If these boats are built in the area, perhaps you could just get a builder to make one a bit wider to make it plane better, and/or add some spray rails. The cheapest/best might be to get a "fugimori" with a 120-150hp motor, and add spray rails.
    Rails keep the spray from getting you all wet and can also make it plane better.

    I understand you are not wild about the fugimori, but if it will do the job, it might be ok. would not plan on delving deep into boat design or consulting NAs if I were in your shoes. If not the fugimori, find a big panga somewhere.

    Whatever you do, the trips you are talking about are going to be long, in any boat. You could easily spend 4 times the money and fuel to get a trip only marginally easier, in a bigger and supposedly "nicer" boat. Just my 2 cents...
     
  10. Loveofsea
    Joined: Jan 2007
    Posts: 147
    Likes: 6, Points: 0, Legacy Rep: -68
    Location: Southern California

    Loveofsea New Member

    How cool Tom~!

    I just happened to stop by here and saw your link to the article about my skiff. I'm still running these seas like you wouldn't believe:)

    Ravencry,

    I have had a number of engines on the skiff and i do meticulous logging of my miles traveled and gallons burned--i know my milage down to 3 decimal points. I have ued Merc 75HP 2-stroke, a couple of 90HP2-stroke, a 90HP 4-stroke Honda, a 100HP Yamaha 4-stroke and most recently a 115HP Merc Optimax 2-stroke. The opti gets better milage than any of the other engines, hands down. I get .2NM better milage with the Opti than the Yamaha. Over the course of a trip, that saves a couple of gallons over the yamaha, for the same weight! Hope this helps...

    BTW, I bet it's fun to make a run like that!
     
  11. Fanie
    Joined: Oct 2007
    Posts: 4,603
    Likes: 170, Points: 63, Legacy Rep: 2484
    Location: Colonial "Sick Africa"

    Fanie Fanie

    Tourist sometimes are like sheep. The first time they see something beside the boat all 50 of them are going to run to the same side to see, you have to make sure the boat is not going to go over.

    Personally I would consider a catamaran hull, 12m long and 6m wide. It will offer a lot of passenger space and stability. Twin motors would make it more maneuverable and if one motor develops a problem the other will save the day. A 60hp motor per hull will have it fly.
     
  12. apex1

    apex1 Guest

    Fanie he is transporting people on the Amazon river. They are NGO volunteers. A cat is not the right solution for him as we found out on another thread.
     
  13. Ilan Voyager
    Joined: May 2004
    Posts: 1,186
    Likes: 100, Points: 63, Legacy Rep: 758
    Location: Cancun Mexico

    Ilan Voyager Senior Member

    The boat is not the problem, the actual one Fugimori will do the job at the cheapest price and the least effort.

    The true problem is the the 60 HP Yamaha outboard, probably from the Enduro series. Very thirsty boy, it can be only beaten by Australians drinking beer. This engine has one of the worst specific consumptions of the 2 stroke history and at full open throttle with his little 60 HP it's not far from 350-400gr/HP/hour if the carbs are a bit worn. To worn a Yam carburator is very easy; dismantle it once without care as it's done in most latin american countries. Or forget to grease the choke.

    I would keep the money for 4 stroke outboards and keep them at 75-80% of the max power close to the maximal torque and the best specific consumption lets say about 220-235 gr/HP/hour. It´s 40 % better specific consumption.

    That means a 100 HP 4 strokes with injection, or 2*50 HP. That have some advantages: the 50 HP are very light, simple with carbs and quiet, and you have 2 engines... The Mercury or the Yamaha 50 HP are equivalent. Lone "con" the consumption is not as good as with the injection but far better than the 2 Strokes. The lone Enduro Yamaha with a decent consumption is the 85 HP 3 cylinders, but needs a good mechanic as the carbs are pretty complex. Some trials of propellers would be a good idea...generally the propellers have too much or not enough pitch on this kind of boats, as everybody use the propeller sold with the outboard regardless of the size and weight of the boat. I live in a third world country, and I know how the boats are not tuned or worst detuned... A bow pointing to the sky is useless so keeping the boat at a 4 to 6 degrees is the most easy way to save money and to get speed.

    Having to build a faster boat is expensive...keep the money for the people who need it.
     
  14. Ilan Voyager
    Joined: May 2004
    Posts: 1,186
    Likes: 100, Points: 63, Legacy Rep: 758
    Location: Cancun Mexico

    Ilan Voyager Senior Member

    Baeckmo, thanks for reminding the evidence in boat design...Apex thanks for the PDF, very useful. What's this rage of trying to design with some freeware when there are plenty of good and proven plans for a few bucks? a very small and tiny fraction of the price of the boats...
     

  15. Ilan Voyager
    Joined: May 2004
    Posts: 1,186
    Likes: 100, Points: 63, Legacy Rep: 758
    Location: Cancun Mexico

    Ilan Voyager Senior Member

    Ravencry, if you need a really fast transportation on river or lake, ie flat water by true necessity like ambulance etc... go to the hovercraft. Very different story but very efficient. No boat at equal power can follow an hovercraft on flat water... It has its cons also (noise mainly), but low waters in dry season are not more a problem. The French army uses hovercrafts in French Guyana.

    The technology is simple, the construction uses common materials and it´s powered by a car engine. The Duratec 4 in line engines from Ford are good candidates (the 2.3L is used by all the latin american Rangers so the spare parts are available, and weights less than 120 kg naked) apart the Suzuki and Subaru (very exotic in South America)

    To give you an idea of the thing
    http://www.hovercraft.com/content/index.php?main_page=index&cPath=35_55

    At 80 bucks is a good idea to buy the plans to examine them.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.