boat trailer tongue weight

[rob v]

I've done a bit of research and wondered if anyone could give me the benefit of their experience. I bought a used boat a couple of years ago and have suspected since I bought it that my tongue weight was too heavy for the unit. It's a 1750 crestliner fishawk with a 115 mercury optimax.

 

I've calculated the weight of my boat at about 1100 lbs, the motor at about 375 lbs (both weights from the manufacture spec sheets), and the trailer at about 300 lbs or so. With fuel, batteries etc I'm guessing another 350 lbs or so. so approx 2000lbs.

 

Using a bathroom scale I measured the tongue weight at about 365 lbs.

 

According to some of the literature I've read the tongue weigh should be between 10 and 15% of the total trailer weight. This would put me in the 200-300 lb range - say 250 to split it.

 

My trailer is a bunk trailer (4 bunks) and the transom of the boat sits flush with the end of the bunk. My trailer is a single axle trailer.

 

My guess is each trailer is different but would it be a simple matter of moving the boat back on the trailer until that desired weight is achieved i.e. moving the winch bracket back a bit and adusting bunks and keel rollers as necessary so the boat isn't pulled so far up on the trailer ?

 

If so - any idea how much I should expect to have to move the boat back ? 3 inches, 6 inches, a foot ?

 

I'd appreciate any input from anyone who has dealt with/knoweldge of this issue.

 

thx. Rob V

[irishfield]

Are the springs held on with U-bolts...loosen and slide the whole axle assembly forward on the frame... until you get the tongue weight you want.. BUT before you do that, take it to a scale and actually weigh the trailer loaded exactly how you would usually tow it.

[rob v]

Yes - I believe it is and I thought about that also - but I was worried about making sure I didn't get the axle out of allignment and thought it would be eaiser just to move the boat back a bit. Perhaps moving the axle forward is a better option ?

[irishfield]

If the trailer tracks good now.. just mark the original location of the ubolts on each side.. at rear edge of ALL Ubolts. Then move the assembly forward equally and snug back down. BUT go weigh the whole trailer at a public scale first... so you have a true weight.. then calculate the 9 to 15% tongue weight you want at the ball. 9% if using a lighter vehicle... closer to 15% if using a good truck.

 

To move.. loosen the Ubolts a tad.. block the wheels so they can't move and try backing up the frame with the vehicle. Weight the tongue. Repeat 'till you get it where you want it for tongue weight.. check that the ubolts are equal distance from the starting marks.. adjust if necessary and snug down. Go have fun!

 

Shoreland'r actually spells out 6% on single axle and 5% for a dual axle trailers tongue weight. I think that's a little light.. but they are in the trailer business!!

 

They also suggest that an inch of axle movement equates to about 15 lbs of tongue weight.

 

http://www.shorelandr.com/pages/f_trstep3.html

 

Once you are on the above link... check the other adjustments to be sure your boat is sitting where it should be on the trailer to start with.

Edited February 1, 2010 by irishfield

[DRIFTER_016]

Also moving the boat back is not the way to go. If you wove it back there will be a section that is no longer supported by the bunks.

This will cause what is know as a hook(a section that is bent/curved up in front of the transom) in the hull which causes handling problems. The best thing to do is move the axle.

Edited February 1, 2010 by DRIFTER_016

[rob v]

Thanks for info - much appreciated. I'll do some more research.

 

I'm not 100% sure how easy it'll be to move the axle but I'll have look the next time I can (boat's in storage off site). But if the axle move looks to be too complicated and I have to move the boat back a bit - perhaps I can move the bunks back to match it so I don't have the problem you're referring to Drifter.

 

Where exactly does a guy find a public scale to weigh everything anyways ?

[irishfield]

What make of trailer is it Rob?? My Shoreland'r.. the axles/springs etc are mounted to a frame of their own.. loosening the eyebolts allows this frame work to slide under the actual trailer frame... unlike some that the spring perches are bolted in place right to the trailer frame... and moving the ubolts with load on them would have the spring spreading the unbolts apart.

Edited February 1, 2010 by irishfield

[DRIFTER_016]

Thanks for info - much appreciated. I'll do some more research.

 

I'm not 100% sure how easy it'll be to move the axle but I'll have look the next time I can (boat's in storage off site). But if the axle move looks to be too complicated and I have to move the boat back a bit - perhaps I can move the bunks back to match it so I don't have the problem you're referring to Drifter.

 

Where exactly does a guy find a public scale to weigh everything anyways ?

 

 

The Dump.

[irishfield]

The Dump.

 

Yep... transfer station.. dump. They weigh you coming in and then out and charge you the difference. Ask the guy if you can take the trailer off the hitch and weigh the boat and slip him $10

[rob v]

The dump - great idea. never thought of that.

 

My trailer is a northtrail - and from what I've been able to figure out online (again I'll have to look again when I'm at the boat next) it looks like the later example you've described wayne where the spring perches are bolted in place right to the trailer frame - in a situation like that I assume I would have to take the load off the axle - i.e. jack the trailer up and then move the axle after loosening the springs from the frame.

[irishfield]

Easy enough though Rob with a couple of Jack-alls.. or a couple sissor style truck jacks. Why I originally stated to mark the back side of all the ubolts so you know that you've moved them all identically to keep the spring arch the same.

 

Now if your fenders are bolted to the frame without adjustment... you're back to moving bunks and bow stop!

Edited February 1, 2010 by irishfield

[DRIFTER_016]

The dump - great idea. never thought of that.

 

My trailer is a northtrail - and from what I've been able to figure out online (again I'll have to look again when I'm at the boat next) it looks like the later example you've described wayne where the spring perches are bolted in place right to the trailer frame - in a situation like that I assume I would have to take the load off the axle - i.e. jack the trailer up and then move the axle after loosening the springs from the frame.

 

Very easy to do. 1/ lower tongue jack as far as it will go. 2/ put axle stands under the back of the trailer frame. 3/ jack up tongue jack until wheels are off the ground.

 

A version of this works well if you have to replace or work on your bunks too.

1/ lower tounge jack 2/ place axle stands under back corners of boat hull (use a pair of 2X8 pieces to spread the load and protect the hull) 3/ jack up tongue 4/ block up hull forward 5/ lower tongue

Hull should now be floating above the trailer.

[rob v]

Thanks again - some good info - we'll have to look into it.

[smally21]

is the tongue weight causing a problem? too much is better than too little. but if your vehicle doesn't like it than moving the axles is certainly the way to go. if it is a well fitting trailer you'd hate to mess with the bunks. tandem axles are easier to guess the balance point as the equalizer between the axles is level when the trailer is level. we usually set axles at balance point - 10" depending on the boat/engine configure. try about 4" forward should make the difference you are looking for. the axles move surprisingly easy once unloaded. knock the ubolts forward with a hammer after loosening and the axle assembly wants to follow. good luck!

[JohnF]

Thanks for info - much appreciated. I'll do some more research.

 

I'm not 100% sure how easy it'll be to move the axle but I'll have look the next time I can (boat's in storage off site). But if the axle move looks to be too complicated and I have to move the boat back a bit - perhaps I can move the bunks back to match it so I don't have the problem you're referring to Drifter.

 

Where exactly does a guy find a public scale to weigh everything anyways ?

 

Our dump weighs all garbage coming in and trucks going out. I'd check with one of the guys I know there. Weigh the whole rig then drop the trailer and weigh the hauler.

 

oops. Sorry. Just saw that someone beat me to the dump.

 

JF

Edited February 2, 2010 by JohnF

[archer379]

your in london the flying J truck stop has a cat certifed scale if the dump doesnt work

[Sinker]

is the tongue weight causing a problem?

 

That is the million dollar question. There is no sense moving anything if it tows alright and your vehicle can handle it.

 

S.

[rob v]

I'm towing it with a ford ranger and it's "squatting" a bit more than I'd like to see. I was thinking about beefing up suspension a bit ( air supports etc), but I'm thinking I might try to lessen the tounge weight a bit. If I can reduce it by say 100 lbs or so - say 6 inches of axle movement - that might help a lot, that would still leave it at 250 lbs . I checked with proctors - they're guestimating my tongue weight should be in the 200lb range.

 

and thanks for the flying j info - i might try there - that'd be nice and convenient. do you think they'd charge me anything to do that ?

Edited February 2, 2010 by Rob V

[dannyboy]

If you have the weight at the tongue and at the wheels and distance between the tongue and axle the calculation is straight forward to figure out how much weight shift you get for each inch of movement of the axle - similar to weight and balance calculations on aircraft.

Do some physics review on arms and moments or post the numbers and I can figure it for you.

 

You can also find weigh scales at livestock feed companies.

 

Dan

Edited February 2, 2010 by dannyboy