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Thread: DF140 What size boat can it push??

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    Member Akgramps's Avatar
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    Default DF140 What size boat can it push??

    I am looking at a project boat and considering using a DF140 w/prop for power and wondering if its gonna be too much boat.
    Its a 25 foot Aluminum hull w/ a decent V bottom, 76" wide bottom.
    The hull is relatively light, maybe 1000 pounds as it sits w/o floor, cabin, tanks anything, completely bare.
    I supect it will end up weighing about 2500- 3000 pounds when we are done.
    I have the DF on a riverboat currently (w/jet) and thinking about using it on this hull w/prop.
    So I would like to hear from folks that are using this motor w/prop and find out just how big and heavy of a boat will it push?
    Thanks.........
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    Member theultrarider's Avatar
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    I think that may be pushing a bit imo. But with that said, look at all the 22' hewes around with 100 and 115's on them! If I were to try to power your boat with a 140-150, it would be the suzuki. My dad also has one on his boat and it is a great motor. Why I think it may handle what you have in mind is because they very low gearing in the lower unit compared to the others. Essentialy making them a "high thrust" motors like alot of the 9.9's and 50's that are offered. They swind a much larger prop vs the others. It won't be a speed demon, but I but you could prop it to push it well.

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    Got one on a 22ft pacific skiff with a homemade cabin on it.
    Wish i would have gone with the 150/175 at least.
    It does all right but takes awhile to get on step with a big load.

    The smallest i would go on the boat you describe is 175 preferably a 200.

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    Moderator Paul H's Avatar
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    Ideal is 25# per hp, gross weight. So figure out hull, engine(s), fuel, gear, people, etc. Thus a 140 is ideal for a 3500# load. I figure my hull and engines are around 2000#, add 350# for fuel, 50# ice, couple hundred pounds for misc junk and upwards of 1000# of people and that puts me at ~3500# gross. The suzi 140 has no problem pushing that load 31 knots wot, or cruising 22-24 knots.

    I'm thinking you vastly underestimate the weight of a 25' aluminum boat, unless it is a very thin hull I expect it's closer to 2000#'s.

  5. #5

    Default my impression

    a co-worker just got one on his 20' woldridge Alaskan and considering the described performance with both a prop and a jet-foot, it sounds like one of these darn things could push a Northland Barge and get 8 gph to boot...

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    I may be underestimating the hull weight, it is not on a trailer so I dont have a good way to weight it at this time.
    I see a 25' C-Dory on craigs w/ a DF140

    http://anchorage.craigslist.org/boa/1292691443.html

    According to the C-Dory website this boat weighs 3600#, no motor, fuel, fisherman & gear.
    Seems underpowered according to what I am hearing, maybe I will call the seller, Its a fine looking boat, but I am only interested in what the motor will do, hate to call just to chat if not serious.
    This is all research and home work for me at this time, I hope to get something more ocean worthy in the next year or so and trying to make educated decision. Also trying to decide if the hull I have is worth the effort its gonna take to make it seaworthy.
    That brings me to another question about C-Dorys, I know they are considered a very seaworthy hull. But when I look at them they appear to be almost flat in the back, is there something I am not getting?
    “Nothing worth doing is easy”
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    Terrible outboards, you should sell it cheap while you can....to me

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    Quote Originally Posted by Yukoner View Post
    Terrible outboards, you should sell it cheap while you can....to me

    I can make you a heck of a deal, its the delivery thats gonna hurt
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    Member Rod in Wasilla's Avatar
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    Quote Originally Posted by Akgramps View Post
    That brings me to another question about C-Dorys, I know they are considered a very seaworthy hull. But when I look at them they appear to be almost flat in the back, is there something I am not getting?
    What is it about a flat-bottomed dory-style hull that would make you question its seaworthyness?
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    Quote Originally Posted by Rod in Wasilla View Post
    What is it about a flat-bottomed dory-style hull that would make you question its seaworthyness?
    I didnt say I question its seaworthyness, I know they are that. seems to me Tolmans are a similar design. I am just trying to understand how they work with a flat bottom.

    Earlier in the year I was comparing Hewescrafts and Seasports and they both have a considerable V to the bottom unlike the Dory's. And I thought some V is desireable or neccescary to have a boat that works decently in the ocean?

    I know how my riverboat is on the ocean and just wondering how the shape of the Dory's enable them to be so capable in the ocean?

    Its just my ignorance of these things and trying to understand hull shapes better, the Dorys must have some fore & aft rocker to the hull?

    Can anyone shed any light on this for me?
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    Moderator Paul H's Avatar
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    I haven't run a C-dory, my understanding is that the flat bottom will pound in a smaller chop than a semi v. That is the down side of the flatbottem, you have to slow down sooner.

    On the other hand, the flat bottom will rock less while fishing, so it has an upside. Also the flat bottoms need less hp to get on step, so they are more efficient in calm water.

    The advantage of the flared sides of the dory is that when waves come in from the side, you have "reserve boyancy" which is a way of saying they will rock away from the wave.

    There are alot of factors that go into "seaworthiness". Number 1 is the captain staying out of trouble. That comes from both knowledge and experience. It's much better to hole up when the water looks questionable then to see what your boat can do. As far as design factors that make a boat sea worthy, to an extent there are tradeoffs but to me an ocean boat should have a decently high bow with a fairly steep V to cut through the waves, reasonably high sides to keep the water out, some flair to the sides and enough hp for less than ideal situations.

  12. #12

    Default C-Dorys

    I've heard that these boats cut the waves just fine, however, if your speed is ever slightly too high, they will pound the crap out of you. Just heresay at this point. Talk to an owner for the real skinny.
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    Quote Originally Posted by Paul H View Post
    I haven't run a C-dory, my understanding is that the flat bottom will pound in a smaller chop than a semi v. That is the down side of the flatbottem, you have to slow down sooner.

    On the other hand, the flat bottom will rock less while fishing, so it has an upside. Also the flat bottoms need less hp to get on step, so they are more efficient in calm water.

    The advantage of the flared sides of the dory is that when waves come in from the side, you have "reserve boyancy" which is a way of saying they will rock away from the wave.

    There are alot of factors that go into "seaworthiness". Number 1 is the captain staying out of trouble. That comes from both knowledge and experience. It's much better to hole up when the water looks questionable then to see what your boat can do. As far as design factors that make a boat sea worthy, to an extent there are tradeoffs but to me an ocean boat should have a decently high bow with a fairly steep V to cut through the waves, reasonably high sides to keep the water out, some flair to the sides and enough hp for less than ideal situations.
    Paul,
    I have always admired the Tolmans, and looked at a few, they are usually in the water so I can not see the hull shape very well. Are the hulls similar to the C-Dorys?
    “Nothing worth doing is easy”
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    Member Tolman24's Avatar
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    Quote Originally Posted by Akgramps View Post
    Paul,
    I have always admired the Tolmans, and looked at a few, they are usually in the water so I can not see the hull shape very well. Are the hulls similar to the C-Dorys?
    I have a Tolman 24' Jumbo. The deadrise (V) at the stern is 12* and amidships it is 18*. At the bow it has a pretty sharp entry. It also has what is referred to as chine flats on the outside edge of the bottom. I believe this helps reduce the rocking at rest. I do not have trim tabs and when on step passengers walk form side to side without notice. It runs pretty well in the chop but when it gets rough you need to throttle back.

    As an example, I was at Pony Cove and Agnes last Saturday. I headed back about 4:30. The water was a bit rough and in order for my wife to stop gritting her teeth and flinching each time I came over a wave I throttled back to about 15 - 18 mph until Calisto. After Calisto I ran about 22 - 25. After Caines head I ran at regular cruis spped of about 25 - 28. The boat could take it, the passengers didn't like it.

    With the fairly flat bottom I am powering the 24' with a Suzuki DF115. It gets on step without noticing any real bow rise. It will stay on step to about 15 mph but even below that you just get more bow up and a decrease in mileage. With good water I can cruise at 25 mph all day at about 4.3 MPG. Top speed WOT is 33 mph in good conditions.

    Last Saturday about 11 am we headed around Cape Resurrection to head for some halibut fishing. The water was kind of lumpy and we decided to go to Pony and Agnes after silvers instead. Some of the passengers get sea sick and I decided anchoring up wouldn't be fun. With that said I wasn't concerned with the boats ability to handle conditions, but rather the human factor.

    I usually have 6 adults and 2 dogs aboard for day trips. I can fish 4 pretty well. Largest group for a day was 8 adults (family visiting). Got a little tight fishing but sight seeing was great.

    I am sure that you could look up the CDory specs to get an idea of the bottom. They are a nice looking boat.

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    Moderator Paul H's Avatar
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    This is off of the c-brats forum



    Here's a not very good shot of Ken Chace's Tolman Jumbo



    I'd say asside from the differences in the hull bottoms, the c-dorys are flat, tolmans are a semi V, the hulls are fairly similar in design.

    One big difference for Tolmans is they are generally the lightest hulls you'll find in their size and configuration. So what will work well powerwise for a Tolman will be typically not enough power for a hull that may apear similar in dimensions. Asside from the Tolmans, I'd really question using a 140 horse on a 24-25' boat, ok for a 22, but likely marginal on the larger boats.

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    You really need to find the degree of "v" or deadrise in your hull at the stern. You can do it by using straight edges/levels and measuring the distance/amount of "v" from the keel or centerline ouward toward the chines. Boat needs to be dead level side to side to determine accurately I think. The other guy did mention that Suzi's can run a bigger prop; want to make sure that although that may be true, still 140 hp is 140 hp and you want to make sure you're not over propped and your motor is running in it's effective RPM range. All things considered, boats ALWAYS weigh more than we want them to or what is realistic.
    Just slap another 140 on there and you won't wonder if you have enough oomph.

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    Default DF140 What size boat can it push

    Hmm... We can steal some ideas from the official forum. And here we can also discuss new articles and interviews - theyre usually in English, and till theyre not translated in Russian, we can speak about them here.

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    Gramps, just re proped my DF140 with a new design Suzuki has. I don't understand the physics of it all and I can see a slight difference between the new and the other props. Going to try a 19 pitch and see what I get. The motor is on a 24' Sea Ark.

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