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Thread: Pram Perimeters

  1. #1
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    Default Pram Perimeters





    I am currently looking at the overall size of the tender/sailing dingy design. I know that I want a usable load capacity of approximately 500 pounds and a hull weight of <50 pounds. I started my design spiral at 9 foot long and 4.5 feet wide with approximately 6” draft and 12” freeboard.

    After building a model and looking at capacity, material, internal space, etc. this has led me to experiment with different lengths/widths for this project.
    My gut tells me that the smallest dingy would fit a footprint of 8 foot long and 4 foot wide (just to be nominal) which led me to the following. Coast guard rule of thumb for capacity is length times width divide by 15 yields usable capacity in pounds divided by 150 pounds yields number of persons allowed on board. Referenced here:

    Calculating Your Boat’s Capacity
    On boats less than 20 feet in length with no capacity plate, use the following rule of thumb to calculate the number of persons (weighing 150 lbs. each, on average) the vessel can carry safely in good weather conditions.
    Number of people = vessel length (ft.) x vessel width (ft.) ÷ 15
    For example, for a vessel 18 feet long by 6 feet wide, the number of persons is 18 times 6 (or 108) divided by 15, which equals seven 150-lb. persons (or a total person weight of 7 x 150, or 1050 lbs.).

    I know that this is rough, but since I am in Florida with 100’s of other people on boats who may or may not understand the rules of the road, I would like to stay within the legal limits. Also because I am not a licensed naval architect, I just want to play it safe.

    Thus the 4’x8’ dingy would yield the following:
    Usable capacity of 320 pounds or two people max.
    38 pound hull
    500 pound displacement would equal 8 inches of draft

    My original design was the following:
    4.57 foot width and 8.85 length with 6.5 inches of draft @ 500 pounds of displacement
    This yields the following:
    Usable capacity of 400 pounds or two and 1/2 people max.
    42 pound hull

    My final design is a lengthened hull:
    4.5 foot width and 10.0 length with 6.0 inches of draft @ 500 pounds of displacement
    This yields the following:
    Usable capacity of 450 pounds or three people max.
    46 pound hull
    Reaching my 500 pounds plus or minus would only be slightly overloaded, or just mostly dead!

    So therefore the following can be said: the material cost increase from original design to final design is minimal, the usable load is more in aligned with what I wanted, and the design is more closely related to my original idea and parent hull design.

    Are there any pros and cons for the design chosen for this type of design/build, which you can chime in on? Any experience with this type of project?
    Description: Skin (composite) on plastic frames (composite)… designed as a tender for a larger ship, used to carry supplies to and from, needs to be easy to row (for exercise), needs to be a day-sailor for just the fun of it, and could be needed as emergency flotation life raft if one is not available. Also would like to use a small <5 HP outboard offset on the transom.

    Of course, the 500 pound capacity would not be used for sailing or rowing… just as the tender to shuttle back and forth for shore excursions etc…
    Thanks for the input.





    BJD Bowman

  2. #2
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    Default Re: Pram Perimeters

    That's a fine looking pram. I expect that it will do exactly as you want it to do.

  3. #3
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    Default Re: Pram Perimeters

    John Welsford's Tender Behind has a 350 kg(4-5 peeps) capacity, weighs about 70# and is a proven design

    sail, row, tow, up to 5hp... and th'aint ugly neither

    http://www.duckworksbbs.com/product-...nderbehind.htm

    sw
    "we are the people, our parents warned us about" (jb)

    steve

  4. #4
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    Default Re: Pram Perimeters

    CLC,s Passagemaker.



    Its a bit bigger at 11ft 7in x 57in, but the total load is 650lbs. Johns stuff is obviously within the "rules".

    His Eastport pram which is similar size to your spec....



    7ft 9in x 48in with a load capacity of 375lb. But his smaller 6ft Eastport ultralight has a capacity of 400lbs....



    I have no idea of your regulations regarding loads and certifying. Small dingies in Europe have to be able to support the total load even if flooded, if built and put on the market, which takes up a lot of internal space.

    I think if you are only going to go max load while transferring stuff to the boat from shore, then like most tenders doing the same job, they end up being a lot lower in the water than under usual use. Your 50lb target is light for the capacity, i think, Dave Gentry 55lb Skin on frame is close to your size, 7ft 11in x 47in, with a suggested capacity of 400lbs.




    At the end of the day, only you know how exactly you will use your boat, and your drawing looks good. If conditions are marginal and you have a heavy load, then do the sensible thing and make 2 trips.

  5. #5
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    Default Re: Pram Perimeters

    I've built one of CLC's Passagemaker 12' prams. It has a 650 pound payload but weighs in the 90-100 pound range, so may be outside of your design criteria. With the gunter-sloop rig option, it sails extremely well, with great windward performance. With just me (200 pounds) a small cooler and the requisite safety gear, she sails very bow up to ease her way into the waves. I've found that if I can get her to heel about 15°, her bottom/garboard chine parts the waves very smoothly. I'll be taking her on the Salish 100 this summer for an extended cruise, fully loaded, so we'll see how she handles that. It took approximately 250 hours (including both sails) to splash her. I beefed up the skids, gave her a graphite bottom and a stainless rub strake on the skeg for our rough PNW beaches. I have about 30 minutes of rowing experience with her (with the mast/sail/boom in the way), so not much of an opinion there.

    I've also built one of their Eastport prams, and can say that it's a lot of fun for a small crew or solo in protected waters, but I got swamped doing the Duck Dodge on Lake Union in Seattle and was unable to self-recover due to the fact that the gunwales were 1-2" underwater once righted. Some additional flotation would have helped. As such, it's way outside of your design criteria for payload.

    With that being said, I think that CLC's designs have a modern twist on classic designs aesthetic, which make them very attractive to passersby while you're rigging and ready to shove off.
    Last edited by CaptainSkully; 01-21-2019 at 08:49 AM.

  6. #6
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    Default Re: Pram Perimeters

    Quote Originally Posted by Gib Etheridge View Post
    That's a fine looking pram. I expect that it will do exactly as you want it to do.
    Thank you sir, you are kind and thoughtful, and I appreciate your comment.

  7. #7
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    Default Re: Pram Perimeters

    The hard unfortunate reality is that tenders get banged-up, abused, and stolen.

    You don't actually want the prettiest tender at the dock.

    My 2 cents is to keep it simple, sturdy, and painted. That is what I have evolved over many years of being at a mooring, and gunkholing.

    Have a look at the 10 ft pram on my Drake thread. It's a very practical tender. Huge capacity, and tows with very little drag, quite dry.

  8. #8
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    Default Re: Pram Perimeters

    After building an 8' child's boat I have been experimenting around with small boat designs to build in the basement over the winter (currently working on a 9 1/2' v-bottom stem dinghy of my own design).

    I don't think the capacity rules necessarily apply to tenders, there are so many variables to consider that can add or subtract capacity on a given "footprint" (length X width).

    Last winter a fellow from the Netherlands overwintered on his 50' yacht at our yacht club. In the spring when the water was open I tried out and measured his tender.

    It was a 9' long and 4' wide stem dinghy, fiberglass and it seemed very heavy; he was guessing ~57 kg, which is 125lbs. He didn't have to hoist it up by hand, but on the shore the two of us could barely carry it. I cannot remember how many people he said he had in it at one time, but it was more than three. I was struck by how deep this boat was, and figured that this was at least part of the secret of getting the most carrying capacity out of a short boat. It also had a harder bilge than yours and very low sheer, resulting in higher freeboard in the middle. It felt very stable. I don't know if it would tow well, he always carried it on deck.

    Dutch tender 0152.jpgDutch tender 0154.jpg

    Your pram looks scaled down from the rowing model pictured in your first post, keeping the same general proportions. It has a lot of the nose out of the water, meaning that the waterline length is pretty short for its overall length. Most of the prams designed as tenders have their bow transoms bigger and their noses shortened up. You could probably lop off about 1' off your design and retain most of its carrying capacity. The pram tender designs out there generally also have less rocker than yours.

    You might want to carry air bags if you don't want to build in buoyancy tanks. At any rate, your target weight of 50lbs would be difficult to achieve in plywood; you are probably looking at 4mm plywood or skin on frame. Tanks provide stiffness, which means you might be able to use thinner ply and have less solid lumber thwarts. For example, the 9 1/2' nutshell pram is built from 6mm plywood, doesn't have tanks, and is advertised as weighing 100lbs (not sure if that includes sailing parts and sails). Intended capacity listed as 3-4 people. https://www.woodenboatstore.com/prod...enders_-_prams

    Paul Gartside's 9' X 4'10" pram has a weight of 90 lbs listed (6mm ply, tanks, only one solid wood thwart, no sailing bits). Capacity not listed in pounds or number of people, but described as "large".
    https://store.gartsideboats.com/prod...ram-design-127

  9. #9
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    Default Re: Pram Perimeters

    This pram is an 8' x 4' "Coot" - a Nick Schade design. It will have a 2 rowing positions, 2 buoyancy tanks and is expected to weigh about 65 lbs. I tossed in the seats to give an idea of the layout. I will glass the interior today and fillet in the seats later this week.






  10. #10
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    Default Re: Pram Perimeters

    Quote Originally Posted by Dave Hadfield View Post
    The hard unfortunate reality is that tenders get banged-up, abused, and stolen.

    You don't actually want the prettiest tender at the dock.

    My 2 cents is to keep it simple, sturdy, and painted. That is what I have evolved over many years of being at a mooring, and gunkholing.

    Have a look at the 10 ft pram on my Drake thread. It's a very practical tender. Huge capacity, and tows with very little drag, quite dry.
    I built a Selway-Fisher pram, Skylark 8, as a tender. 4mm ply, ocoume, flat bottom and 3 strakes each side, stitchandglue, and exc. Rig less then 20kg. We towed it along Spain across the Med, kids learned to row and sail in harbour Barcelona and around Balearics. Best dinghy I ever had.

  11. #11
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    Default Re: Pram Perimeters

    I like the design and I think that you're in the ballpark of the capacity you want. Another inch of freeboard would still look OK to me.
    You might check your design vs. the LF Herreshoff pram.
    .

    If the boat is to be used as tender to a larger boat, I'd recommend you apply Gunwale Guard, despite its weight. It'll save a lot of paint scuffs.

  12. #12
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    Default Re: Pram Perimeters

    Quote Originally Posted by BOI View Post
    You might want to carry air bags if you don't want to build in buoyancy tanks. At any rate, your target weight of 50lbs would be difficult to achieve in plywood; you are probably looking at 4mm plywood or skin on frame. Tanks provide stiffness, which means you might be able to use thinner ply and have less solid lumber thwarts.

    Paul Gartside's 9' X 4'10" pram has a weight of 90 lbs listed (6mm ply, tanks, only one solid wood thwart, no sailing bits). Capacity not listed in pounds or number of people, but described as "large".
    https://store.gartsideboats.com/prod...ram-design-127
    I agree that the fifty pound criteria will be difficult to meet with a pram that will hold up unless great care is taken with it at docks and landings. Is the fifty pound requirement needed for launching, carrying on a car or because it would be hauled onto a dock or deck? It should be mentioned that Gartside pram above is skinned with epoxy and glass cloth. It was designed and built for the previous owner of our boat and is an excellent stable tender. Gartside has drawn a 14' version also.

    https://goo.gl/images/chtdiw
    Last edited by rbgarr; 01-22-2019 at 05:46 PM.

  13. #13
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    Default Re: Pram Perimeters

    With very light boats, flotation becomes an issue. I.e., if you swamp it, has it enough buoyancy to support you?
    Without air bags, I'd expect no useful flotation from a SOF boat.
    If you're careful, 70 lbs. is a good target for a 10' pram of strip composite, stitch&glue, or glued lapstrake construction. Cold molded could be a bit less.

  14. #14
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    Default Re: Pram Perimeters

    I built a seat fore-and-aft, notvathwartships, and glued 2" pink foam under the whole length. Lots of floatation.

  15. #15
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    Default Re: Pram Perimeters

    thanks...I have seen this.

  16. #16
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    Default Re: Pram Perimeters

    Quote Originally Posted by skaraborgcraft View Post
    CLC,s Passagemaker.



    Its a bit bigger at 11ft 7in x 57in, but the total load is 650lbs. Johns stuff is obviously within the "rules".

    His Eastport pram which is similar size to your spec....



    7ft 9in x 48in with a load capacity of 375lb. But his smaller 6ft Eastport ultralight has a capacity of 400lbs....



    I have no idea of your regulations regarding loads and certifying. Small dingies in Europe have to be able to support the total load even if flooded, if built and put on the market, which takes up a lot of internal space.

    I think if you are only going to go max load while transferring stuff to the boat from shore, then like most tenders doing the same job, they end up being a lot lower in the water than under usual use. Your 50lb target is light for the capacity, i think, Dave Gentry 55lb Skin on frame is close to your size, 7ft 11in x 47in, with a suggested capacity of 400lbs.


    At the end of the day, only you know how exactly you will use your boat, and your drawing looks good. If conditions are marginal and you have a heavy load, then do the sensible thing and make 2 trips.
    I spoke with CLC and they only sell full size patterns and not real plans... So this is a no go. The small seams to be too small and the large is just a bit too large.

    I wanted to split the difference and build with Skin on Frame.

    Thanks.

  17. #17
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    Default Re: Pram Perimeters

    Quote Originally Posted by CaptainSkully View Post
    I've built one of CLC's Passagemaker 12' prams. It has a 650 pound payload but weighs in the 90-100 pound range, so may be outside of your design criteria. With the gunter-sloop rig option, it sails extremely well, with great windward performance. With just me (200 pounds) a small cooler and the requisite safety gear, she sails very bow up to ease her way into the waves. I've found that if I can get her to heel about 15°, her bottom/garboard chine parts the waves very smoothly. I'll be taking her on the Salish 100 this summer for an extended cruise, fully loaded, so we'll see how she handles that. It took approximately 250 hours (including both sails) to splash her. I beefed up the skids, gave her a graphite bottom and a stainless rub strake on the skeg for our rough PNW beaches. I have about 30 minutes of rowing experience with her (with the mast/sail/boom in the way), so not much of an opinion there.

    I've also built one of their Eastport prams, and can say that it's a lot of fun for a small crew or solo in protected waters, but I got swamped doing the Duck Dodge on Lake Union in Seattle and was unable to self-recover due to the fact that the gunwales were 1-2" underwater once righted. Some additional flotation would have helped. As such, it's way outside of your design criteria for payload.

    With that being said, I think that CLC's designs have a modern twist on classic designs aesthetic, which make them very attractive to passersby while you're rigging and ready to shove off.

    Thanks... See above... I spoke with CLC and cannot do a SOF. but they are nice.

  18. #18
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    Default Re: Pram Perimeters

    Quote Originally Posted by Dave Hadfield View Post
    The hard unfortunate reality is that tenders get banged-up, abused, and stolen.

    You don't actually want the prettiest tender at the dock.

    My 2 cents is to keep it simple, sturdy, and painted. That is what I have evolved over many years of being at a mooring, and gunkholing.

    Have a look at the 10 ft pram on my Drake thread. It's a very practical tender. Huge capacity, and tows with very little drag, quite dry.
    David,

    Thanks.. I do agree with you... very good points.

  19. #19
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    Default Re: Pram Perimeters

    Quote Originally Posted by BOI View Post
    After building an 8' child's boat I have been experimenting around with small boat designs to build in the basement over the winter (currently working on a 9 1/2' v-bottom stem dinghy of my own design).

    I don't think the capacity rules necessarily apply to tenders, there are so many variables to consider that can add or subtract capacity on a given "footprint" (length X width).

    Last winter a fellow from the Netherlands overwintered on his 50' yacht at our yacht club. In the spring when the water was open I tried out and measured his tender.

    It was a 9' long and 4' wide stem dinghy, fiberglass and it seemed very heavy; he was guessing ~57 kg, which is 125lbs. He didn't have to hoist it up by hand, but on the shore the two of us could barely carry it. I cannot remember how many people he said he had in it at one time, but it was more than three. I was struck by how deep this boat was, and figured that this was at least part of the secret of getting the most carrying capacity out of a short boat. It also had a harder bilge than yours and very low sheer, resulting in higher freeboard in the middle. It felt very stable. I don't know if it would tow well, he always carried it on deck.

    Your pram looks scaled down from the rowing model pictured in your first post, keeping the same general proportions. It has a lot of the nose out of the water, meaning that the waterline length is pretty short for its overall length. Most of the prams designed as tenders have their bow transoms bigger and their noses shortened up. You could probably lop off about 1' off your design and retain most of its carrying capacity. The pram tender designs out there generally also have less rocker than yours.

    You might want to carry air bags if you don't want to build in buoyancy tanks. At any rate, your target weight of 50lbs would be difficult to achieve in plywood; you are probably looking at 4mm plywood or skin on frame. Tanks provide stiffness, which means you might be able to use thinner ply and have less solid lumber thwarts. For example, the 9 1/2' nutshell pram is built from 6mm plywood, doesn't have tanks, and is advertised as weighing 100lbs (not sure if that includes sailing parts and sails). Intended capacity listed as 3-4 people. https://www.woodenboatstore.com/prod...enders_-_prams

    Paul Gartside's 9' X 4'10" pram has a weight of 90 lbs listed (6mm ply, tanks, only one solid wood thwart, no sailing bits). Capacity not listed in pounds or number of people, but described as "large".
    https://store.gartsideboats.com/prod...ram-design-127
    Thanks.. very good points. I like what you have to say and appreciate your input.

  20. #20
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    Default Re: Pram Perimeters

    Quote Originally Posted by bheys View Post
    This pram is an 8' x 4' "Coot" - a Nick Schade design. It will have a 2 rowing positions, 2 buoyancy tanks and is expected to weigh about 65 lbs. I tossed in the seats to give an idea of the layout. I will glass the interior today and fillet in the seats later this week.
    Very nice build... thanks for the comments. Post pics when finished or a link.

    Thanks again

  21. #21
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    Default Re: Pram Perimeters

    [QUOTE=JimConlin;5792132]I like the design and I think that you're in the ballpark of the capacity you want. Another inch of freeboard would still look OK to me.
    You might check your design vs. the LF Herreshoff pram.
    .

    If the boat is to be used as tender to a larger boat, I'd recommend you apply Gunwale Guard, despite its weight. It'll save a lot of paint scuffs.
    /QUOTE]

    Nice... great comment... thanks for your idea, I'll add the guard for sure.

  22. #22
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    Default Re: Pram Perimeters

    Quote Originally Posted by JimConlin View Post
    With very light boats, flotation becomes an issue. I.e., if you swamp it, has it enough buoyancy to support you?
    Without air bags, I'd expect no useful flotation from a SOF boat.
    If you're careful, 70 lbs. is a good target for a 10' pram of strip composite, stitch&glue, or glued lapstrake construction. Cold molded could be a bit less.

    Good points, thanks... will consider

  23. #23
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    Default Re: Pram Perimeters

    Hey All,

    I found the parent hull through another post on this site. I had been trying to find it for months. I should have looked on this site first! Here it is... It's a French designer with the pram "Laita".

    http://www.vivierboats.com/en/product/laita/



    I'm now going to build a balsa wood model with the data that I have found online, and compare it to my latest hull design changes.
    Now that I have an idea of the length and width of the parent hull it was a bit easier to tweak my design.

    I am still not sure about the size of the little pram. Now that I see the length of these boats, I'm thinking that the extra length could be a good thing.

    My last model appears to be too short and stumpy as I have built a 1-1/2"=1'-0" cardboard hull of the original design that was posted in the first post above.

    I just finished the cardboard model tonight after I had already decided to adjust the hull. I want to make the hull closer to the parent hull proportions. This is the latest revision below.






    This newly revised hull is designed at 10' long and 4 foot wide. My only issue now on the hull design is if I should scale it up to closer match the parent hull which is 11-1/2' long and 4-1/2' wide. My issues stand from what I want to do with this boat and how I want to build it.

    Skin on Frame could get heavy if the boat is 12 feet long. And then there is the issue of where to keep it on board. It would take up more space unless I made the longer boat nesting. But then that is a whole other set of issues.

    So now I am pondering the length / Scale while I build the parent hull and this newest hull revisions out of balsa wood.

    I'll upload the picture of the first hull once I get them on the computer.


    Thanks, for all the support and let me know what you think about the scale... should it be 10 feet or 12 feet in length?

    Thanks again.

    Here are the chine coordinates of the new hull if anyone wants to play with the design.

    1


    0.1529 0.0000 0.4974
    5.0276 0.0000 0.0000
    9.9792 0.0000 1.0784


    0.1529 0.6262 0.4974
    5.0276 0.6905 0.0000
    9.9873 0.2341 1.1242


    0.1351 0.9177 0.5913
    5.0276 1.1811 0.0924
    10.0006 0.3684 1.1992


    0.1033 1.1508 0.7710
    5.0276 1.6050 0.3576
    10.0186 0.4773 1.3014


    0.0606 1.3059 1.0127
    5.0276 1.9031 0.7590
    10.0404 0.5578 1.4248


    0.0000 1.3721 1.3557
    5.0276 2.0344 1.3086
    10.0773 0.6068 1.6331


    EOF

    Have a great weekend.
    Last edited by bjdbowman; 01-26-2019 at 09:39 PM.

  24. #24
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    Default Re: Pram Perimeters

    I found the original parent hull:

    This is an idea of what I am working toward.



    Below are two designs overlaid on top of the parent hull.



    Above is the 10 foot version and below is the 12 foot version so that you can see my design compared to the parent hull.




    The Red Design is what I have come up with and the gray is the Parent Hull.

    Let me know.

    Thanks,

  25. #25
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    Default Re: Pram Perimeters

    CLC's Passagemaker (which I just built) is a bit narrower in the bow. While this may create a little less buoyancy, it may lead to a slightly finer entry. I also find it a bit more aesthetically pleasing than the chubbier version.

    PM.jpg

  26. #26
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    Default Re: Pram Perimeters

    All,

    I'm uploading the original Model although this will not be built, it was my first attempt at the proportions.







    I'll update the design below...

  27. #27
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    Default Re: Pram Perimeters

    Quote Originally Posted by CaptainSkully View Post
    CLC's Passagemaker (which I just built) is a bit narrower in the bow. While this may create a little less buoyancy, it may lead to a slightly finer entry. I also find it a bit more aesthetically pleasing than the chubbier version.
    Yeah, I like the design, but they do not have building plans, just patterns for a stitch and glue. Thanks, How do you use your passagemaker? what would you change? How long did your build take? I watched the video of CLC's building sessions. Kinda cool.

    Thanks again...

  28. #28
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    Default Re: Pram Perimeters

    Latest Version of the design... I shortened it up as to keep below 10 feet. I cannot deal with the weight and length so this decision is done.

    Some other things to think about is how to deal with the transom. I have been kicking around the idea of making it more modern in the stern. I have started that direction in this new design. I also added some width in the back (made the transom area wider) and shortened up the bow and made the bow transom even smaller, like the parent hull. Let me know what you think of the direction.

    Thanks,






    I like the fact that the strakes are less curvy... Anyway this is where I'm at in the spiral.

    Thanks,

  29. #29
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    Default Re: Pram Perimeters

    Why the reverse slope on the stern ?

    I would have thought the older way , ( perpendicular ) is preferred by most ?

    Easier to hang a rudder if you want to rig it later too ?

  30. #30
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    Default Re: Pram Perimeters

    Quote Originally Posted by bheys View Post
    This pram is an 8' x 4' "Coot" - a Nick Schade design. It will have a 2 rowing positions, 2 buoyancy tanks and is expected to weigh about 65 lbs. I tossed in the seats to give an idea of the layout. I will glass the interior today and fillet in the seats later this week.
    Nice, Job... Looks great. What are you going to do with it? (purpose)... How many hours to build? I like the trunk seat. Did you make a strongback with moulds jig for the strip planking? What else can you tell me about your build?

    Thanks for sharing.

  31. #31
    Join Date
    Jan 2019
    Location
    Melbourne, FL, USA
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    32

    Default Re: Pram Perimeters

    Quote Originally Posted by beam reach View Post
    Why the reverse slope on the stern ?

    I would have thought the older way , ( perpendicular ) is preferred by most ?

    Easier to hang a rudder if you want to rig it later too ?
    I'm just playing around with the stern. I was going to look at an open stern like a modern day racing sail, with the ability to climb into the boat from snorkeling/diving etc. Just something that I'm thinking of, nothing is final yet, just in the early days. The first few designs had a traditional pram transom. I'm still just thinking out-loud.

    Thanks,

  32. #32
    Join Date
    May 2016
    Location
    Pacific drifting
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    472

    Default Re: Pram Perimeters

    I understand , you are going well so far.

    Will be interesting to see the final iteration.

    Nice lines.

  33. #33
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    Jan 2019
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    32

    Default Re: Pram Perimeters

    Quote Originally Posted by beam reach View Post
    I understand , you are going well so far.

    Will be interesting to see the final iteration.

    Nice lines.
    Thanks... it nice to receive encouragement... I'm learning as I go. Next is to build the balsa wood model of this latest hull and check to see how it floats and to check the drag or resistance in the pool vs. the software. Once I have settled on the hull form, I can then start playing with the construction method, frames, rig, etc.

    I still have a long way to go before I actually start to build the little boat.

    Thanks again.

  34. #34
    Join Date
    Apr 2002
    Location
    Corvallis
    Posts
    284

    Default Re: Pram Perimeters

    You asked a couple of questions about my pram build. The purpose - it's nothing more than a tender for a trailer sailor. The pram build started about a week before Christmas. I'm not keeping track of the time, but the intention was to make it a quick process. The strips were leftovers from a couple of kayaks and the ply was leftover from a recent sailboat build. It is built atop a ply strongback with the molds (1 foot spacing) attached egg crate style. I suspect that this boat is going to receive minimal TLC and maximum abuse. The interior is faired just enough to avoid air pockets under the cloth. Admittedly, it's a bit rough. Today I glassed the gunnels.



    There are some additional pictures at the end of the "Gartside 170" thread . I hope you end up building your design, it looks like fun.

  35. #35
    Join Date
    Jun 2010
    Location
    Between Bourgeoisie and Proletariat - Australia
    Posts
    3,012

    Default Re: Pram Perimeters

    Whats the initial stability going to be like with that lovely curvy bilge?

    And, look what someone did with a nutshell; http://urbanboatb1.web704.discountas...struction1.htm
    Philip K. Dick — 'Reality is that which, when you stop believing in it, doesn't go away'.

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