Instructions for fitting a boat to a new Venture Aluminum Bunk Trailer:
1. Make sure your tow vehicle has the right ball size [2" for singles and small tandems. 2 5/16" for tandems over 6,000 # boat load capacity and all triple axle trailers. With capacity equal or greater than the weight of your boat with all tanks full and gear and the weight of the trailer.
2. Make sure you have the right electrical connector and that all leads have power when the appropriate light or action is set on. Ideally you have a flat 5 connector if the trailer has standard surge-disk brakes or a round 1.5" dia. RV type 7 pin AND a 7 : 5 adapter you could buy at Wal-Mart or most auto parts stores. If you ordered your trailer with the optional EOH electric brake controller to operate the hydraulic disk brakes, you need a round 1.5" dia. RV type 7 pin connector on the tow vehicle.
If you have surge brakes and only a flat 4 connector, you will be fine for most towing situations. If you have to back up either uphill or where there are speed bumps or large potholes, you will need to plug the end [5th] pole of the trailer wiring harness into the 2nd pole [1st female connector next to the ground connector] and put your parking lights on. This will energized the 5th pole with 12 volts which will operate the solenoid on the back of the surge brake master cylinder, effectively disabling your trailer brakes. Drum brakes on a boat trailer usually do not work and if they do, doesn’t work effectively in reverse, hence no need for this solenoid and wiring. Disk brakes work just as efficiently in reverse as forward.
3. Measure your boat from the bow eye to the transom. This is the bow eye length.
4. Transom of your boat should hang off the end of the bunks 1-12 inches. Make sure bow stop is far enough forward to allow this and move it one foot further forward than that for the first loading.
5. Make sure the target bunks are set to the lowest by loosening the set screws so they are mostly out of the way for the first time pick up.
6. The main bunks will likely not have to be moved, unless they are set where they would rest on something like a water pickup or hull transducer, or right at the point of a longitudinal stringer or angle on the boat bottom. If so move them in towards the center of the trailer the minimum movement necessary to clear. It is important to get the bunks set as wide as possible for lateral stability.
7. Lower your trailer on the hopefully steepest ramp you can easily use so the the target bunks are just barely sticking out of the water. This position is several feet further up the ramp than when you launch and float your boat off the trailer.
8. Put the boat on the trailer in contact with the target bunks. Release out enough winch line to hook it up. Put the winch in low gear by moving the turning handle axle so the little gear on it makes contact with the gear nearest the handle, to make it easy to turn the winch handle.
9. Do not winch it all the way up to the bow eye as you left about a foot to spare. You can reduce or eliminate repeating steps 9-11 by:
a. if your boat is already on its old trailer and the tongue weight/balance is good, put tape on the boat over the center of the center axle on triple axle trailers or right between the axles if tandem.
b. if 9a is not possible, google search “boat make model” and ‘trailer’ then click on ‘images’ to just see pictures of your boat model on a trailer. Note on the picture that part of the boat that is over the center of axles above, like a letter of the boat name or the edge of a window or or some part. Use this point to load your boat on the new trailer centered on the axle set center.
10. Pull the boat far enough out of the water to measure where the transom is compared to the back of the bunk. For rear engine power boats only: Repeat steps 7-10 to get the transom hang over to 1-12 inches. Steps 9a or 9b are more accurate loading plans.
11. Move the boat up to flat ground. Check the approximate tongue weight by blocking tires on trailer and completely unhooking trailer ball connector. Turn the tongue jack and feel the pressure. It should be hard to turn but not awfully hard. Better to have too much tongue weight than not enough. You may have to repeat steps 7-10 to get the tongue weight about right.
Correct Tongue weight is way more important than overhang at the back of the bunks. If too light your trailer will sway side to side at high speed. It is ever does this; gently release power to slow down very gently.
12. Move the bow stop and winch stand back and up or down so the yellow bow roller is touching the boat with the bow eye just behind and below the bow roller.
13. Attach transom straps. Tighten winch and attach safety chain to bow eye.
14. Drive slowly [under 55 or 50] home
15. The tongue weight should be about 7% of the total loaded weight of boat and trailer and fuel and gear, so about 500# for a tandem and about 900# for a triple. You can accurately weigh the tongue weight by using a 4 ft. 4x4, pile of blocks and a bathroom scale. Set a pile of blocks to 4 inches below tongue height, and 12 inches center to center to one side of tongue. Put the scale with blocks on top of it 3 feet opposite the other pile of blocks. This leverage will mean your bathroom scale will read 1/4 of the tongue weight, so if the bath scale says 200, the tongue weight is 800. See trailering PowerPoint download on my web site to see a diagram of this.
16. Adjust target bunks up snug to the hull. The target bunks carry very little load while trailering. Their primary purpose is when putting your boat back on the trailer; they guide the bow towards the bow stop. Their secondary purpose is reducing fore-aft rocking of the boat while on the road, as the aluminum I-beams flex more than the steel counterpart. This flex is not only not bad; it is good to cushion the blows of road bumps to your boat.
17. Re-Tighten all bolts you have adjusted and wheel lug nuts after ten miles of towing.
18. Have fun boating. Remember the tip when picking up your boat to have the trailer further up the ramp than you do when you launch. Winching your boat several feet to the bow eye will results in a better centered boat and less load on the tow strap when you pull out and the boat will be right up to the bow eye. If you put the trailer all the way out and put the boat on it, when you pull out there will be a gap between the bow eye and the bow roller which is UNSAFE for two reasons-- the tongue weight will be too low making the boat and trailer sway at speed. If you have a panic stop or have an accident hitting something in front of you, the boat will slide forward and may cause damage due to the momentum it has built up moving before it hits the bow stop. The bow stop is designed to keep the boat stopped in its position only if the boat is not moving on the trailer when it hits the stop.
Feel free to call me from the boat ramp while fitting if you have any questions. Sandy 888-387-1963 or 253-376-8273 revised 5-31-15
Ball Size: All trailers at 6000 boat capacity or less use a 2 inch ball
All trailers at 7000 boat capacity and up use a 2 5/16th inch ball
Ball Height: 14 in tires require 20-21 inches top of ball to ground
15 in tires require 22-23 inches top of ball to ground
16 in tires require 23 inches
(some cases may require you reversing your receiver and placing ball on top to achieve height)
Surge disc brakes are a 5 flat, like most common flat 4 with an added prong = 5th wire activated by reverse lights to shut off brakes when backing. Most newer vehicles with tow package come with a 7 round which has a reverse wire in it, therefore, a 7 to 5 adapter is used, or you can wire a 5 flat. The 5th, going to reverse wiring is usually a light blue wire in your harness. Adapters can be purchase from us or found at local marine or hitch stores. Let us know before pick up or delivery if you need one.
Electric Brakes require a 7 pole round plug like most new vehicles come with for RVs
To Tighten Lug Nuts:
For your trip home, bring 13/16 in lug or torque wrench to torque lug nuts after the boat is on trailer and rolling a few miles, but before getting on freeway. If trailer model is commander series 6000 or 8800, wrench must be thin walled to fit in the lug nut holes.
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