Results 1 to 16 of 16

Thread: Best ground clearance for boat on a trailer?

  1. #1
    Join Date
    Feb 2006
    Location
    Pennsylvania
    Posts
    7,755

    Default Best ground clearance for boat on a trailer?

    I'm planning my next project, and what I thought was a simple question is getting complicated.

    The boat will be CLC's Autumn Leaves. The bottom runs out to a skeg that is no higher than the belly of the boat. Now I plan to keep this boat in a garage, which means it's better if low on the trailer. And I want it to be easy to launch an retrieve at any ramp, which also means it's better to be low on the trailer.

    But the boat will extend about 6-1/2 feet behind the axle when set up to get the tongue weight where it needs to be. I was thinking about putting the boat on a trailer wide enough to drop the hull between the wheels, putting the skeg as low as 18" over the road. But in the past two days, two delivery trucks have gouged my driveway trying to back in -- it goes up a slope from the road.

    So this has gotten me to thinking -- I don't want the boat to ride so low that the skeg is scraping the ground all the time. But if too high, it will be harder to launch and retrieve and might not even fit into a standard garage door of 7', or even an 8' door.

    The question -- is there a rule of thumb for what in SUV talk is the "exit angle" for a boat trailer? I've had several boats and trailered them thousands of miles, and not once have I dug the transom into the ground. But all of those boats have either sat high on the trailer, or had sterns that swept up from the midbody quite a bit. Thoughts?
    -Dave

  2. #2
    Join Date
    Dec 2005
    Location
    Vancouver Island
    Posts
    159

    Default Re: Best ground clearance for boat on a trailer?

    Having had gouges in my driveway from my trailers from both the long trailer tongue and the overhanging boat transom when 'others' have been doing the driving; I would suggest choosing a height for launching first; some ingenuity and care in the driveway (approaches to trailer parking) will solve that gouging issue when you are doing the driving.

  3. #3
    Join Date
    Oct 2013
    Location
    dfw
    Posts
    1,012

    Default Re: Best ground clearance for boat on a trailer?

    your dilemma used2 worry me too

    over the years i have developed a rule that says the transom of all my boats is directly supported by the trailer

    problem solved when its trailer parts and not boat parts draggin ;-)

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

    steve

  4. #4
    Join Date
    Aug 2006
    Location
    Rockford, IL
    Posts
    8,521

    Default Re: Best ground clearance for boat on a trailer?

    This one is considered "low", and it's never dragged on the pavement. The 3-strand lanyard used to haul it vertical runs right around the bottom curve of the rudder fin.DSCF2631.jpg

  5. #5
    Join Date
    Sep 2010
    Location
    Bainbridge Island WA
    Posts
    2,206

    Default Re: Best ground clearance for boat on a trailer?


    Gets kind of interesting when you start thinking about the vertical gyrations your hitch is doing when your tow vehicle changes attitude.
    This might be an opportunity to get an adjustable air ride suspension put together for the boat trailer. Lower it for launch, crank it up for travel.
    Steve

    Boats, like whiskey, are all good.
    R.D Culler

  6. #6
    Join Date
    Jul 2013
    Location
    Aquitaine
    Posts
    711

    Default Re: Best ground clearance for boat on a trailer?

    My 15ft Oughtred boat sits on a full length main tube with wishbone swing axles & coil springs. Clearance under the point where the wishbones are hinged is about 6".
    Not grounded yet and it makes launching much easier with keel rollers and I keep my wheel bearings dry. BUT, I don't have a sloping driveway....

    Edit: Just checked out in the barn and the trailer clearance is 8" and the keel 15" off the ground.
    Last edited by Andrew2; 12-01-2017 at 06:35 AM.

  7. #7
    Join Date
    Feb 2006
    Location
    Pennsylvania
    Posts
    7,755

    Default Re: Best ground clearance for boat on a trailer?

    This might be an opportunity to get an adjustable air ride suspension put together for the boat trailer. Lower it for launch, crank it up for travel.
    Now that would be something. Scarf parts from an old Citroen and go for a totally custom fit.

    Since I posted the question I went out and took a picture of the drive so I could figure the angle where it meets the street. It seems to be 11 degrees, give or take a degree. So I made up this illustration/worksheet. If the boat sits high enough to just scrape the ground as I leave the drive, I'll only need 16" of clearance under the stern.
    Having the trailer frame run all the way back makes a lot of sense, but I just don't see them manufactured to the right proportions. Anything that long is designed for far more weight than I'll be hauling. Another strategy is to put skid plates on the ends of the trailer frame that wil fall below the blue line on the diagram. As a backup, a metal shoe on the skeg would be a good idea, too.
    What the diagram does show is that fitting the boat in a 7' garage door is iffy (there'll be spars bundled up over the cabin), but an 8' door should be enough.

    And that Shearwater really does ride long and low. I'm surprised it's never touched the ground.

    Trailer proportions.jpg
    -Dave

  8. #8
    Join Date
    Sep 2010
    Location
    Bainbridge Island WA
    Posts
    2,206

    Default Re: Best ground clearance for boat on a trailer?

    You might take a look at what happens when the trailer is being towed. At some point if the hitch starts rising above the “level” height the back end moves down . It all depends on how long your bill is
    Steve

    Boats, like whiskey, are all good.
    R.D Culler

  9. #9
    Join Date
    Oct 2013
    Location
    dfw
    Posts
    1,012

    Default Re: Best ground clearance for boat on a trailer?

    when i picked up my diesel trawler she was on a trailer that scared me

    though built quite heavily the trailer didn't go back to protect the prop & rudder(similar to your skeg worries) and on the 1600+ mile trip home i turned into a basket case every time we stopped to eat, for fuel or in a motel lot fearing i would drag and break some expensive parts

    this pic shows the problem



    once home i began the search for an appropriate(according to garp) trailer source and ultimately found one not far(only 2 hours) from our normal cruising ground's base camp

    i took the rig to the manufacturer and explained my feelings and desires to the owner who wholeheartedly argeed with me

    his price for a one of a kind custom trailer was the same as trailers of that size were going for in the area and he didn't even ask for a deposit

    i showed up on the agreed upon date and time and was told to go to lunch because there were 4 trailers in front of me blocking access to the lift :-(

    at 1pm i showed back up and the shop was ready and waiting as 2 young men started hauling raw materials out of the storage building out back

    at 7pm that evening my boat was lowered onto her new ride



    the next morning just before lunch break i left with a proper trailer that balanced just right and towed delightfully



    you can see better from this pic that as prescribed the trailer extends all the way to the transom and properly protects the rudder and the prop



    the longer tongue allows me to easily launch w/o dunking my truck body or even wheels

    btw the new trailer allowed me to launch and load solo whereas the old one required 3 on the ground w/ 1 in the truck :-O

    i frequently get comments about my trailer being so wide and having a long tongue which is when i simply tell the nay sayers that i believe the trailer sould cradle and protect my baby/investment...

    look into local manufacturers and GO VISIT with them

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

    steve

  10. #10
    Join Date
    Feb 2006
    Location
    Pennsylvania
    Posts
    7,755

    Default Re: Best ground clearance for boat on a trailer?

    Steve,

    You have me convinced. Regardless of the boat height over the pavement, the trailer frame needs to extend all the the back -- even if it is a double-ender with a pointy tail. Looking at trailer options, I think that if I start with the load capacity and width that works, I can then lengthen the tongue to get the overall length that I need. But because these trailers are usually balanced for boats with outboards, (axle well aft) pulling the sailboat forward over the lengthened trailer will put the axle much too far aft. I'll have to be sure that can be adjusted.

    And yes, to the first Steve, pulling a trailer is an extremely dynamic situation. Some bolt their spare tire to the frame vertically. This prevents water from collecting, but it also puts it closer to the road reducing the "ramp break over angle" in the SUV illustration. I much prefer to bolt it horizontally on top of the frame. I had a notion that I could carry this boat very low to the road which would be slick most of the time, but a terrible idea a critical .01 percent of the time.
    -Dave

  11. #11
    Join Date
    Oct 2013
    Location
    dfw
    Posts
    1,012

    Default Re: Best ground clearance for boat on a trailer?

    Dave, when you have a trlr built for your boat the manufacturer will balance the load properly up front

    you can also request a cross member located so the centerboard can't fall thru and drag on the ground during transit

    or a wide longitudinal bunk for the entire keel to ride on

    some manufacturers offer telescoping tongues and/or folding tongues which fit in less space

    and the quest goes on...

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

    steve

  12. #12
    Join Date
    Jan 2010
    Location
    Sweden,Scilly Isles, Siberia
    Posts
    8,062

    Default Re: Best ground clearance for boat on a trailer?

    It really comes down to angles. My folkboat had a lot of its aft end over the rear axle, admittedly quite high, the main problem with that was being aware of the arc the transom would swing through on a tight turn and parked cars. There was an extendable bars to carry a lighting board, and that would be the first thing to start scraping. Cant say i ever had an issue, and thats with 12ft behind the axle and 10in under the axle. Obviously if your parking /driveway ramp is that steep that trucks are scraping out, its something you need to check on. You could always shift the axle aft, aslong as you do not exceed you nose weight on the hitch. Certainly worth the effort to get the trailer set up right.

  13. #13
    Join Date
    Oct 2005
    Location
    The Netherlands
    Posts
    82

    Default Re: Best ground clearance for boat on a trailer?

    I have the same problem with the daggerboards of my catamaran. Some fellow multihullers use foam for the lower end, glassed in, so when hitting something hard it breaks without further damage. You might do the same, but I would be inclined to omit the skeg completely. On my lugger I wanted it for rowing, but your boat is not intended for that. For directional stability I would use the rudder fixed with a few lines. Frank

  14. #14
    Join Date
    May 2005
    Location
    upstate ny- thats north of the catskills
    Posts
    612

    Default Re: Best ground clearance for boat on a trailer?

    woxbox, I've got my 24x6 ft canal boat on a loadrite skiff trailer I bought new just for this boat. my boat has 6 inches of rocker and is flat bottom like yours, yours has more rocker. I can't take any pics til next week, but my trailer goes all the way to the transom. I use cross bunks, not lenghtwise so I'm supporting the sides of the square boat, not the soft bottom. the axles are adjustable fore and aft. its worked great. Loadrite has numerous sizes to choose from. I can post pics Wednesday if you want. I store the boat in a barn with a 7' high door.


    http://www.loadrite.com/trailers/loa...axle-skiffjon/
    Last edited by openboater; 12-09-2017 at 11:20 AM.

  15. #15
    Join Date
    Feb 2006
    Location
    Pennsylvania
    Posts
    7,755

    Default Re: Best ground clearance for boat on a trailer?

    I'm supporting the sides of the square boat, not the soft bottom.
    Good point there. This boat has 600 pounds of lead ballast laid under the sole amidships. My main thought is to double up the bunks and make sure there's good contact in that area. The rest of the boat is a rigid plywood box structure.

    FF -- This boat will be rowed for auxiliary power, so the skeg needs to stay. I could come up with some sort of crafty skeg that slides off the boat for transport, but my object with this project is to keep everything as simple and straightforward as possible. My previous boats have been work enough to launch and pack up for the ride home -- 1 to 2 hours of sweaty labor. I'm getting to old (or lazy) for that!
    -Dave

  16. #16
    Join Date
    Jul 2013
    Location
    Emerald Coast, FL
    Posts
    401

    Default Re: Best ground clearance for boat on a trailer?

    You can have the trailer built with a drop frame and axle to get lower.






Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •