Project: Boat Trailer Tongue Extension

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Project: Boat Trailer Tongue Extension

Postby jeffd » Mon Jan 05, 2015 11:37 pm

Project: Boat Trailer Tongue Extension

Tongue extension for a San Juan 21 trailer? You might ask, why, for a boat with so little keel-up draft? I've asked the same question. I've owned my SJ21 for about 30 years and have usually managed to get the boat off the trailer, even at some pretty primitive launch ramps. A few times, I've had to back the tow vehicle pretty deep into the water, but still with reasonable success. The last few years, I have been exploring some the lakes on the Colorado River system: Lake Havasu, Lake Mohave, Lake Mead, and Lake Powell. Limited snowfall in recent years has reduced the lake levels in several of these lakes to the point of making it difficult to launch boats. These lakes are reservoirs, so a certain amount of fluctuation is expected, but lake levels down 100 feet or more has made launching boats rather difficult. To make matters worse, the slope of the ramps at these low levels tends to be very shallow.

Here is a photo I took at Lake Mead in April 2014. With the low water levels, the boat ramp is very long. At the water, the slope is very gentle. When I launched, I had to back the van pretty far into the water - almost over the rear axle. That's a lot farther than I'd rather.

1-LakeMead.jpg
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So with a trip to Lake Powell on my calendar in Fall 2014, and knowing the lake levels would be low, I started looking into a trailer tongue extension. After a bit of research, I decided to use a design similar to one I found on about.com. The design uses a piece of square 2"x2" steel tube 1/4" thick by 8' long for the extension, which slides into a standard trailer receiver tube mounted on the trailer tongue. I modified the design a bit, based on what parts I could obtain locally and easily, and at reasonable cost. Here is a photo of the completed tongue extension in action:

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As you can see, the extension gives me a lot of extra length at the boat ramp. This was a test, at my local boat ramp (Coulon Park in Renton WA), which is pretty steep. So even at low lake levels, the extension is not needed here. But I wanted to test the system, and work out all the bugs, instead of finding problems when I get to Arizona.

Below is a closeup of tongue extension, slid into the receiver tube, and its attachment to the trailer.

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I looked around locally for parts, and decided to order a 1 ft piece of square tube, 2.5" x 2.5" 0.1875" thick for the receiver. This piece has more clearance than needed, but makes it easy to slide the tongue into the receiver. The downside is I lost some ground clearance. I used a few short pieces of steel tube for spacers so the tongue would clear the trailer coupler, and to get a bit more ground clearance, the tongue is angled down.
Rectangular pieces of 3" wide steel x 1/4" thick and 1/2" bolts were added to secure the receiver to the trailer. 1/2" threaded rod and brackets were added for vertical stiffness. A standard 5/8" receiver pin secures the tongue extension to the trailer. I ordered all of the steel from Online Metals in Seattle, and picked it at their will-call. I didn't even consider paying for shipping - the 8' tongue extension weighs about 60 lbs!

Photo: Boat just launched-floated off trailer, at Coulon Park. As you can see, the tongue extension gives me a lot of extra length at the ramp.

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To complete the design, I added a few square tubes to the side rails of the trailer, to store the tongue extension, when not in use. The tongue extension is secured to the trailer by a receiver pin at the aft end:

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Since I was using brand new steel, I decided it would be a good idea to paint it. I used spray galvanizing paint. Maybe not the best, and it was hard to get the insides of the tubes, but it was better than nothing. When I launch in salt water and don't need the extension, I put it inside the van, to save it from being dunked in salt water.

As with most projects, I had to make a few design mods, and fine tune it a bit. I knew the 8' piece of hot rolled steel tube would sag a bit. But to get enough ground clearance, I had to angle the receiver tube down, and add a bunch of height to the tow vehicle hitch using a receiver with a lot of lift.

My first real use of the system was at Lake Powell, and it worked well. The lake level was down over 100' and the ramp was not very steep, so the trailer had to go back a long ways into the water, and I was glad for the extra ~6ft+ of tongue length. The van's rear tires did not have to go into the water. The receiver mount was sufficiently secure and stiff. The long tongue does have a bit of flex - a bridge engineer friend of mine reminded me that it is better for the steel to flex some than to break! The long tongue made maneuvering and backing the trailer a bit "different".

Of course this tongue extension is only to be used for getting from the top of the ramp to the water, and then to the parking lot, and for retrieving the boat - all at very low speeds. It is definitely NOT suitable or even legal for any street use.

Another mod that I did was to move the tongue extension storage mounts and the tongue jack to the port side - the tow vehicle driver's side. I was finding that to deploy the extension, I ended up having to hop over the tongue several times. Moving the tongue jack and tongue extension to the tow vehicle driver's side made setting up the tongue extension a lot easier.

One of the things on my list of things to do someday is to reduce the tongue weight on my trailer, by moving the trailer axle forward a bit. I am running about 350 lbs now, which is very nice for towing stability, but causes a lot of bend when I am using the tongue extension.

OK, now I'm prepared to handle some really shallow boat ramps!

Project Costs:

Online Metals: steel tubes, bar $115
eTrailer: coupler $ 25
Local Hardware store: bolts, misc hardware, paint: $ 75
Harbor Freight: receiver with 10" of lift: $ 25

Total Damage: $240
Last edited by jeffd on Wed Nov 04, 2015 11:37 pm, edited 2 times in total.
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Re: Project: Boat Trailer Tongue Extension

Postby cklamp » Wed Jan 07, 2015 11:13 pm

Jeff, a couple thoughts as I've looked into something similar in the past... You can mount a "ball" on top of your extension, and put the trailers coupler onto that. A receiver bolted to the bottom of the trailer tongue with the hole for the "pin" and you'll be nice and straight and supported well. I'd debated a design like that for North American's last year, but we really didn't end up needing one. I do see you have a "skid plate" on the bottom of the coupler area, it might get in the way, but if it comes off having the bar on the bottom would help with the clearance issues. I think this mod would also simplify your connection to the trailer tongue area too.

Another idea you could try to help with the "clearance" and the "sag" in the bar, is a caster wheel, so it spins and turns as you come in and out. Something like this maybe http://www.harborfreight.com/8-inch-pne ... 42485.html I haven't seen a design like that exactly, but i've seen some trailer tongue extensions that had dual wheels in the center where the trailer ball attached to the tongue extension, so my theory is sound:)

Another thought for weight savings... it looks like you're using a full length tube to "stow" it in on the trailer. Cut out the middle section so you just have two short 6" or so sections, and you should save quite a bit of weight as well.

Drew up a pic of my thoughts... Solid bar = trailer tongue, Black outline is your extension.

Later
C

Coupler.png
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Re: Project: Boat Trailer Tongue Extension

Postby jeffd » Thu Jan 08, 2015 4:45 pm

Thanks Christian - what a great idea. I didn't consider mounting the receiver on the bottom, because of the skid, but one bolt and it's off. Bottom mounting would definitely help reduce the sag, and probably reduce the amount of extra metal used on the top mount. I will have to do some playing around with it.

Side rail storage: Sorry, the photo isn't very clear. The tongue is supported by two short pieces (a 6" and a 3") - not one long piece. I ended up using spare pieces from the spacers under the receiver.
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Re: Project: Boat Trailer Tongue Extension

Postby cklamp » Thu Jan 08, 2015 5:13 pm

If you ever want any help or just to bounce some ideas off lmk. I live down in Renton too, and pretty much do all my own fabwork. I also whole heartedly believe in the KISS rule.

Later
C
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