Yup, Reelapeelin hit it right on the head. Too little tongue weight will cause fishtailing.... Too much will cause sagging, misaligned headlights, and uncontrolled "pushing" of the tow vehicle. (But it's always better to have too much rather than too little).
A neat trick to set your tongue weight properly is to take a scale and put it under your trailer jack. First, load your boat so that the end is even with the end of the trailer bunk or the last set of rollers. Once that is done, set your trailer jack to towing height and put the scale under the jack and look at the reading. (I normally set my tongue weight for about 250-300lbs initially, then readjust as necessary.) Adjust your trailer wheels (the pivot point) forward or backwards as necessary to hit that mark. Once you have that done take your boat and trailer out for a test ride. If you can constantly drive at highway speeds without any fishtailing you're done.
According to Shoreland'r trailers, the proper tongue weight is about 6% of your total boat load. They supply the following steps to determine it.
1) Transom should be flush with the end of the bunks/rollers to make sure that tongue weight calculation is correct.
2) To determine proper tongue weight, total the package weight (boat with fuel/battery, motor with maximum horsepower, and trailer) and multiply it by 6% on single axles and 5% on tandem axle trailers. ShoreLand'r suggests that tongue weight may be acceptable in a 5-7% range.
Using an appropriate scale, weigh trailer at coupler, making sure the trailer is at towing height.
Boat with fuel and battery 2000 lbs. Motor 500 lbs. Trailer 900 lbs.
Total Weight 3,400 lbs
Single Axle Figure x 6%
Tongue Weight 204 lbs
3).Using an appropriate scale, weigh trailer at coupler, making sure the trailer is at towing height...
If tongue weight is too heavy, move axle forward an avg. of 10 - 15 lbs. per inch for which the tongue weight is over.
If tongue weight is too light, move axle back an avg. of 10 - 15 lbs. per inch for which the tongue weight is under.
After readjustment, check tongue weight again; proceed as necessary depending on results.
*Note If you cannot properly load your boat onto the end of your trailer, so that the end is even with the end of your bunks/rollers, and then hit the desired tongue weight mark by adjusting your wheels forward or backwards then it's probable that your trailer is too small.
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1987 V20 w/1987 150HP Yamaha on a Shoreland'r Trailer
1978 16.5 Airslot w/1996 120HP Force on a Four Winns trailer
1996 V21 w/1993 200HP Mercury on a Shoreline Trailer
All towed by a 5.7L Hemi Durango.
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Last edited by Destroyer; 06-23-2013 at 01:17 PM.
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