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Proper Trailer Axle Position
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| blacksmithdog |
Posted on 05/29/12 - 7:21 AM
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I just put a new WesCo trailer under my 15' GLS. when I was fitting it, I wanted the boat to be as far forward as possible to fit in the garage. The transom is even with the back end of the bunks.
I haven't weighed the the tongue weight (think I could use a bathroom scale?), but it seems heavy for a 15' Whaler, so I'm thinking I may need to move the axle forward.
To provide a bit more information about the rig, it has a Yamaha F50 on it, the battery is in the stern, and it has a 15 gallon gas tank under the rear seat.
Is there a way to determine the proper location of the axle and what the tongue weight should be for this rig?
I can take measurements when I get home this evening.
thanks
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| kamie |
Posted on 05/29/12 - 7:36 AM
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your trailer tongue weight should be between 7% and 10% of the total rig weight.
http://continuouswave.com/whaler/refe...tions.html
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| CES |
Posted on 05/29/12 - 8:17 AM
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Instead of moving the axle forward, move your boat back on the trailer to redistribute the load.
If garage space is an issue, consider installing a folding tongue on the trailer. It much cheaper and easier to do than moving an axle and the hassle involved with that.
Cliff
1966 13' Sport with a 1993 40hp Yamaha 2 Smoker |
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| Phil T |
Posted on 05/29/12 - 8:45 AM
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In looking at the photo of your boat on the trailer, I would keep the boat in its current location. You want the transom at the end of the bunks, not past them.
Take the rig to a scale and get weight of trailer and boat. Moving the axle is the cheapest corrective action. Trial and error to get it at the right location.
Make double sure axle is perpendicular to the frame when in the right position.
Edited by Phil T on 05/29/12 - 8:46 AM
1992 Outrage 17 I
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| blacksmithdog |
Posted on 05/29/12 - 9:42 AM
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Phil T wrote:
In looking at the photo of your boat on the trailer, I would keep the boat in its current location. You want the transom at the end of the bunks, not past them.
Take the rig to a scale and get weight of trailer and boat. Moving the axle is the cheapest corrective action. Trial and error to get it at the right location.
Make double sure axle is perpendicular to the frame when in the right position.
The boat is on a different trailer now, I got rid of that one.
It's pretty easy to move the axle on my new trailer.
For the perpendicularity, I was planning on measuring from the back corner on either side, is that not accurate enough?
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| gusgus |
Posted on 05/29/12 - 9:57 AM
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To check for alignment to the tow vehicle I would suggest measuring from the center of the trailer ball, to corresponding points on each axle mount.
1987 Outrage 18 W/150 Merc and 8 Honda |
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| Tom W Clark |
Posted on 05/29/12 - 11:11 AM
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I bet the gross weigh of your boat/motor/trailer is about 1500 pounds, so if the tongue weight is about 150 pounds, leave it alone.
A bathroom scale is just fine for measuring the tongue weight. Use a block of wood under the tongue jack if you are concerned about scuffing your wife's scale.
If the tongue jack is back from the coupler very much you will have to do a little simple math to get the true weight at the coupler.
If A is the lateral distance between the jack and the center of the coupler ball and B is the lateral distance between the center of the axle and the center of the coupler ball, then true tongue weight will be:
Weight at Jack x (1 - A/B) = True Tongue Weight
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| blacksmithdog |
Posted on 05/29/12 - 11:52 AM
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I don't know if the total rig would weigh as much as 1500 pounds. Here's my calculation:
Boat - 580
Yamaha F50 - 237
15 gallons of gas - 91
Battery (?) - 50
total - 958
How much do you think a galvanized trailer for a 15' boat weighs, 250-300?
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| Tom W Clark |
Posted on 05/29/12 - 1:17 PM
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Add the weight of the propeller, engine oil, gear oil, rigging harness, cables, gauges, controls, the fuel tanks themselves, fenders, etc. Just call it all 1000 pounds.
A galvanized trailer for a 15 footer is going to weigh 300-400 pounds. Do the math and measure your existing tongue weight before making any adjustments.
If you do need to make an adjustment, we can easily calculate how many inches the axles needs to move.
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| Turpin |
Posted on 05/29/12 - 5:19 PM
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I second the idea of measuring from the hitch to get axle perpendicular. Trust if you do not get it right you axle bearing will get warm, seals may leak and could blow a hub out with continued use as that happened to me. I had measured from the back instead of the hitch and there was a significant difference.
Moving the axle is not a big deal but I suggest measure it a few time before you call it job done and i would measure from the tip of the axle hub to get it exact.
1963 13' Sport 50hp Evinrude
Maintaining a level of sanity that is socially acceptable |
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| gusgus |
Posted on 05/29/12 - 7:49 PM
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Turpin, you are right about measuring twice to get one good result, however you could be a little excessive about heated bearings. Unless you are running tandem axles. Single axles if cocked will only swing the trailer out of alignment and if the bearings get hot, the alignment is way out, or the bearings are likely needing re-pack and adjustment.
I had a tandem trailer with misaligned axles, in two years it ate 12 tires away. The dealer finally replaced the trailer because they were tired of replacing my tires and wheels. They tried many times to fix it and found the trailer was just built out of square.
1987 Outrage 18 W/150 Merc and 8 Honda |
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| blacksmithdog |
Posted on 05/30/12 - 2:07 AM
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I realize that neither of these are scientific, but:
1. My 23 year old weight lifting, rugby playing son and I guesstimated the tongue weight yesterday evening (right as tropical storm Beryl was about to come through) as in excess of 150 pounds, so it's at least 10%.
2. The axle is about 33" in front of the transom, so about 1/5 of the way from the bow.
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| Turpin |
Posted on 05/30/12 - 2:32 AM
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I'd Slide it (It being axle) an 1.5"-2" forward and check it again. Just don't get it to light.
1963 13' Sport 50hp Evinrude
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| Tom W Clark |
Posted on 05/30/12 - 8:10 AM
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Again, why fool around? Take the measurements and figure out exactly how much to move the axle.
The distance from transom to axle is irrelevant. We need to know axle to coupler and the current tongue weight.
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| blacksmithdog |
Posted on 05/30/12 - 2:01 PM
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Tom W Clark wrote:
Again, why fool around? Take the measurements and figure out exactly how much to move the axle.
The distance from transom to axle is irrelevant. We need to know axle to coupler and the current tongue weight.
Tom:
The distance from the axle to the coupler is 180"
The weight on the jack was 260 lbs
Coupler to jack was 40".
Using your math above, the true tongue weight is 202 lbs.
That's 13.5% of the boat weight.
How do I figure out how far to move the axle to make it around 7-8%?
Thanks
Edited by blacksmithdog on 05/30/12 - 4:27 PM |
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| wldrns1 |
Posted on 08/07/12 - 2:09 PM
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Don't mean to jump in but here's an easy way to 'measure the axle'. No measurement is needed.
Find a Parking Lot, hopefully one with large water puddles after a rain, but mostly dry. If no rain, use buckets and pour water over vehicle rear tires or right on the ground in front of rear vehicle tires.
Make sure vehicle and trailer tire pressure is to spec using a gauge. Drive your vehicle STRAIGHT with the empty trailer attached thru the water then onto the dry pavement. Look at the wet tracks left behind. L and R trailer tire tracks should follow in same (mirror image) area as the vehicle tires tracks.
Adjust axle to acheive a straight pull with no 'crabbing'. Done and right!
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| Finnegan |
Posted on 08/07/12 - 3:45 PM
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Tandem axle trailers can be aligned by laying a length of 2 x 4 (or other long straight-edge) against the sides of both tires at center height. The board hould touch each tire at front and back, (four places in total) indicating the wheels are rolling straight. Boat must be off the trailer to slide the undercarriage either forward or backward.
If the front, or back edge of each tire does not hit the board, then the trailer wheels are going "dogstyle" down the road, causing unnecessary wear.
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