Heavy weather capable dingy design

Discussion in 'Boat Design' started by zorton, May 29, 2002.

  1. zorton
    Joined: May 2002
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Southeast, Alaska

    zorton New Member


    I am currently seeking information concering small dingy design. We are looking to add a 8ft dingy to our fairly small (31ft LOA 10.5 beam) sailboat and are trying to learn a bit more about them. Having seen many a bad example of dingy's around the various harbors in southeast we are very interested in finding one that could handle a 2-5hp outboard and two people with fuel and perhaps a bit of gear. My observations have shown me hull shape factors in significantly to a dingy's proformance when loaded and/or under moderate weather conditions.

    Here are the conditions under which we can expect to be out in said dingy.

    -The winds in this area are mostly light from 0mph to 15mph being the norm. Fairly frequently you can expect a stiff breeze of about 20-30. And at least 4-5 times a year 40-50mph gusts with a sustained 20-30mph wind. With that said we don't expect to be trying to make our way back to the boat during a strong blow but would like to be able to make headway against a moderate to light blow.

    -I would love to have the ability to use a 2hp to 5hp outboard. I'm not looking to scream along at 30mph or to pull our boat often but I would like to be able to get home faster than I can row :)

    -My wife and I togther weigh aprox 370 pounds and we can expect a regular load to and from the boat of about 50 pounds. Occasionaly to bring food and other items (cat litter) out we can expect to exceed that load but this would only be occasionaly.

    -The shore line around this area often is rocky and we would be interested in a bottom that could hold up to some abuse. I'm not saying i'm going to bomb along a white water river but I do expect to run into a few rocks.

    Is this possible with a 8ft dingy? Should I look at a bit more lenght to get the proformance i'm after? Are there any popular manufacters that would be able to supply a dingy that would do this or should I build my own (I have some fiberglass layup experence and would not be afriad of attempting a project such as this).
  2. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    To my mind, there is only one sensible option - an inflatable.
    A roll up version would make for easy storage aboard your yacht, but if you're happy to tow it, use davits, or stow it on deck, then a rigid hull would help with the trips to shore. Either way I would recomend buying a good quality dinghy with hypalon or similar tubes.
    We use an 8'6" roll up on our 27 footer. We generally stow it on the boarding platform. We use a 3.3 hp outboard on it. With one aboard, the dinghy is able to plane, the outboard is light and easy to stow. We venture ashore with our 2 dalmations at least 3 times a day - often to rocky shores. As long as the rocks aren't particularly sharp, then the tubes will stand up to them pretty well. One thing inflatables don't like however, is oysters or mussels - these can slice the tubes quick smart.
    The two biggest day to day advantages of the boats is their stability (I can jump up and down on one side of ours with little effect) and the fact that they are unsinkable.
    They won't damage your boat when you bump against it and they are light and easy to store.
    The biggest downside is that they tend to be wet. But if you choose a RIB (rigid bottom) and the tubes sit just clear of the water at rest, then these tend to be a bit drier.
  3. james_r
    Joined: Feb 2002
    Posts: 44
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Toronto, Canada

    james_r Junior Member

    Have you thought about using a nesting dinghy? There are offsets and plans for an 11' by 4'6" (3.35m by 1.37m) dinghy in Dave Gerr's The Nature of Boats. Taken apart, the larger section measures 5'10" (1.78m) in length. The design appears to be well thought out and simple to build and it's free (well you have to buy the book). If you don't feel particularly ambitious you could probably have her built locally.

    She's made from 1/4" (6mm) plywood using the stitch and tape method and weighs about 130 lbs (60kg). If you want to be able to drag her over rocks you could add a heavy layer of glass cloth bedded in epoxy to her bottom.
  4. duluthboats
    Joined: Mar 2002
    Posts: 1,585
    Likes: 43, Points: 58, Legacy Rep: 779
    Location: Minneapolis,MN, USA

    duluthboats Senior Dreamer

    An inflatable is a good choice. If you don’t go that way I would second james’ suggestion of Gear’s, Nester Dinghy. Boatbuilder magazine did a two part series with instructions and offsets. (Jan/Feb 2001 & March/April 2001) Also in the back is an add to where you can buy the joining hardware. ( Glacier Woodworks, Anchorage, AK ) They may also be producing this boat.
  5. Stephen Ditmore
    Joined: Jun 2001
    Posts: 1,389
    Likes: 44, Points: 58, Legacy Rep: 699
    Location: Smithtown, New York, USA

    Stephen Ditmore Senior Member

    There's also the boat that folds up to about the size and shape of a long surfboard - can't think of the name of it off the top of my head. Of the rigid dinghys on the market I'm fond of the Trinka, though it's shape may be better for rowing than powering.
  6. james_r
    Joined: Feb 2002
    Posts: 44
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Toronto, Canada

    james_r Junior Member

    You're probably thinking of the portabote. I've seen them at boat shows but never paid much attention to them. To my eye they're a bit of an ugly ducking, but if you can get past their looks they are probably worth considering. See www.porta-bote.com.
  7. DavidG
    Joined: Jan 2002
    Posts: 52
    Likes: 1, Points: 0, Legacy Rep: 60
    Location: Chichester, England

    DavidG Junior Member

    There is something joyful about rowing a rigid dinghy which cannot be achieved with an inflatable, a pram dinghy might be required if you are trying to get some load capacity within the 8ft constraint, a longer stem dinghy might be considered if going the nested route.

    Although an inflatable maybe more convenient for stowage, in my mind the rigid boat is more satisfying provided it can be accomodated.
  8. Guest

    Guest Guest

    Have you looked at "Dinghy Dogs" http://www.dinghydogs.com/

    They can be added to an existing rigid dinghy, do not degrade rowability much and provide the stability of an inflatable.

    Mike Schooley

  9. Portager
    Joined: May 2002
    Posts: 418
    Likes: 13, Points: 0, Legacy Rep: 325
    Location: Southern California

    Portager Senior Member


    I have studied dinghy/tender options and I have decided that rigid hull boats provide better performance, both powered and rowed and a dryer ride. For my purpose, I like the rigid buoyancy boats (RBB) better than the rigid inflatable boats. They are more durable in the long run (Hyphalon breaks down over time and the rate accelerates with UV exposure) and if the sponsors are flattened on the inside you get more usable space. The downside is RBBs tend to be a little heavier than RIBs, so if you plan to manhandle the tender onto the foredeck you might want to go with the RIB or an inflatable (although you will get a little wetter) or a nesting dinghy.

    The Jolly Boats 8' 6" model http://www.jollyboats.com/Hard Body 8.5.htm would be a choice.

    If you can go to 10' long, the Bullfrog utility tender would be an excellent option. http://www.bullfrogboats.com/tenderutil.htm . The Bullfrog has higher freeboards than most RIBs and RBBs and the sponsors are solid polyethylene foam so they are soft sided and unsinkable. MSRP is $2345.00 without engine and they are located in Bellingham, WA. so the shipping cost would be lower that the Jolly Boat (Ft. Myers, FL.). Bullfrog also has a dealer in Ketchikan, AK.

    Mike Schooley
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.