Setting up new bunk trailer

[wgl333]

Just picked up a Venture bunk trailer for a 95 Wellcraft Eclipse 236 SC, replacing an ez loader roller. Am curious as to where to position the 2 bunks in relation to the hull to allow maximum support and stability.

 

[Texasmark]

Re: Setting up new bunk trailer

I like to position the bunks just outside lifting strakes, actually touching the outside of them. A lot of boats have stringers molded in at the point of the strakes, especially the ones a couple of feet from the keel which is a good place to place a bunk for stability. 2 reasons for doing this: 1. Putting them there makes a "cradle" for the boat to snuggle into when loading and 2. It keeps the bunk damage to the hull, if you will, off a riding surface (when you are in the water) that you want to keep as slick as you can.

The bunk can be vertical or horizontal. Vertical will give your boat the best support as trailers usually don't have but 2 or 3 cross members on the trailer and if you don't support the hull properly you can get a hook in it that really can play .... with your performance.

I get a bunch of cinder blocks and 2x4 pieces and jack the boat off the trailer (keels are tough and a good place to do the heavy jacking), doing one side at a time...don't forget to undo your transom straps. Grin. Is a good idea to have 3 support points under the keel and then an additional light duty jack on the side you want raised so that you can get your new bunk installed.

I remove the old and install the bunks estimating the height. After both are finished, I let the boat down on the stringers and then adjust the stringers. In adjusting, I do one cross member support (attachment point) at a time and it may take several tweaks around the trailer but you have to get it all right: not touching the fender, support of the transom (I usually have my stringer stick out a couple of inches past the transom) bow chock properly positioned....actually, I remove the winch and all and after I get the stringers set to my satisfaction I then reinstall the winch and all and match it all up.

I only use treated wood in the bunks and never reinstall the carpet. Actually there is much less drag on wet wood than wet carpet and they dry out much faster and as a result last much longer than the OEM which usually just uses fir or pine and cover with carpet....no treatment. Yucko!

A little time consuming, but no big deal.

HTH,

Mark

 

[John_S]

Re: Setting up new bunk trailer

Pictures of new trailer and your boat hull would help.

The end of the bunk should extend and be flush with transom, or extend slightly past. Check tungue weight to see if you are in a reasonable range. Not too heavy and not too light, otherwise this can lead to highway handling problems. Adjustment is usually in moving the winch post fore or aft.

 

[wgl333]

Re: Setting up new bunk trailer

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[Texasmark]

Re: Setting up new bunk trailer

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Couldn't access your attachment photo's.

 

[wgl333]

Re: Setting up new bunk trailer




2nd attempt

 

[Starman8]

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2nd attempt

The bunks might serve a better purpose flat than on edge. The more the hull is supported, the better.

The trailer appears to have level cross-members where the bunk hardware is attached. The bunk boards should have an angle equal to the deadrise slope. You can use basic math to calculate positioning.

The full set of keel rollers are nice for launch and retrieve, but shouldn't carry much, if any weight at all. Once you set the bunks, and the boat is fully supported by them, then you can adjust the rollers.

 

[Texasmark]

Re: Setting up new bunk trailer

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2nd attempt

Got it. Trailer looks perfect for the application. It would be nice to know that you have a lifting strake where the bunks are or one within reach of the bunks. I can't tell due to the trim tab being in the way.

On that setup, if you have another like the one(s) near the "keel" (where the keel would be if it had one which is still a good place to jack from) then I would set the bunk under the horizontal part of the strake or better yet, for reasons of ensuring that the boat self centers on the bunks:

First off it appears the the top of the bunks are angled to follow the contour of a pretty good dead rise at the transom which you have. This is ok and you may not have to adjust the trailer at all to fit your boat.....the rollers are really there to keep your keel from contacting the trailer during launching/loading operations.

For the rollers to act as rollers like you had you would have to raise the rollers to lift the boat off the bunks and then it rolls off. You don't want the boat resting on the roller when on the trailer....they can touch, but not depressed. Back in the 60's that's the way you could get a trailer for a fairly light boat; there was a roller lifting hootus that you used to raise and lock the rollers for launch/load. Once out of the water you returned the rollers to the stow position and the boat sat on the bunks.

Today it rests on the bunks and floats off/drives and ditto or winches on with the aft end of the boat floating until the tow vehicle pulls up the ramp and the stern of the boat settles on the trailer.....that's why I like the idea of getting the bunks just outside a lifting strake if you can....helps to make the boat self center on the trailer.

If you don't have a strake handy, or if you do and choose to do the following, the best way to mount the boat is to tilt your bunks to make them perpendicular to the part of the hull that they will touch preferably just outside a lifting strake. That will require a new angled or modified existing set of mounting brackets and if I had the choice I would either double the current number, or move the angled brackets to the outside of the bunks so that when the pressures of loading come into play the bunk is pushed against the bracket rather that the converse which is the way it is currently on that trailer.

Your existing brackets, assuming you choose the minimum effort and leave them where they are, like they are, may want to yield under the weight of your boat and allow the bunks to move out at the top. Finding the trailer mfgr and ordering another set to put on the outside of the bunk, in addition to the ones already on there would be a good choice and probably not that expensive to preclude that occurrence.

If this is not clear or you want more just ask.

Mark

 

[wgl333]

Re: Setting up new bunk trailer

Thanks for the reply....here is where we stand...the closest lifting strake (is just to the right of the trim tab) would require moving the bunks past the flat of the cross member to enable the strake to ride the bunks. Therefore, it looks like I am going to have to get adjustable brackets to allow me to angle the bunk to ride the hull to the inside of the lifting strakes. I have no desire to have the "flat" bunk riding on the angled hull and providing not only minimal support when stored, but and probably as important, when towing and hitting bumps, have the impact focused on a very narrow section of the hull with the corner (albeit carpeted) of a piece of lumber. Or am I looking at that all wrong.

 

[Starman8]

Re: Setting up new bunk trailer

On a 23' boat with a bunk trailer, 4 bunks(FLAT) positioned where your current rollers are may be your best solution. Many websites sell the needed hardware.

The inner bunks, the longer ones support the main hull, and the outside bunks, which are shorter usually are positioned just inside the reverse chine for additional support of the transom/engine weight and assist in centering, then cradling the vessel when transporting.

 

[Texasmark]

Re: Setting up new bunk trailer

Thanks for the reply....here is where we stand...the closest lifting strake (is just to the right of the trim tab) would require moving the bunks past the flat of the cross member to enable the strake to ride the bunks. Therefore, it looks like I am going to have to get adjustable brackets to allow me to angle the bunk to ride the hull to the inside of the lifting strakes. I have no desire to have the "flat" bunk riding on the angled hull and providing not only minimal support when stored, but and probably as important, when towing and hitting bumps, have the impact focused on a very narrow section of the hull with the corner (albeit carpeted) of a piece of lumber. Or am I looking at that all wrong.

Yes, yes, yes.

 

[Texasmark]

Re: Setting up new bunk trailer

Thanks for the reply....here is where we stand...the closest lifting strake (is just to the right of the trim tab) would require moving the bunks past the flat of the cross member to enable the strake to ride the bunks. Therefore, it looks like I am going to have to get adjustable brackets to allow me to angle the bunk to ride the hull to the inside of the lifting strakes. I have no desire to have the "flat" bunk riding on the angled hull and providing not only minimal support when stored, but and probably as important, when towing and hitting bumps, have the impact focused on a very narrow section of the hull with the corner (albeit carpeted) of a piece of lumber. Or am I looking at that all wrong.

I was browsing the West Marine 2011 Catalog (if I boats has them then ok fine), made by C.E. Smith, and they have just what you want for a vertically mounted board. They come in two angles with the 85 degree bracket for the outside of the bunk and the 95 degree on the inside, made of 1/4" galvanized steel at about $12 each. Seems heavy duty to me. They are designed to set a bunk vertical for a trailer with sloping cross members. Could just as well be used to tilt the bunks in either on a flat cross member or to enhance a sloping cross member. West numbers are 11952009 and 11952017.

HTH,

Mark

 

[Texasmark]

Re: Setting up new bunk trailer

On a 23' boat with a bunk trailer, 4 bunks(FLAT) positioned where your current rollers are may be your best solution. Many websites sell the needed hardware.

The inner bunks, the longer ones support the main hull, and the outside bunks, which are shorter usually are positioned just inside the reverse chine for additional support of the transom/engine weight and assist in centering, then cradling the vessel when transporting.

There are two reasons I use caution when using the flat bunks:

1) If inadequate cross members don't exist...which they usually don't the "bending moment" of a 1 1/2" piece of Southern Yellow Pine (specified specifically due to it's deflection under a given load) is third order lower than that of a 5 1/2" board on it's edge and the flat board configuration really only supports the hull where the crossmember exists. For some hulls this is a no brainer as they are built sturdy enough for this to not be a problem. For a boat that apparently survived the gang rollers with their limited support, then it may be a no brainer for his boat.

2) Getting the bunks to fit against the lifting strake and have the boat right (center) itself is more difficult as there is less bunk height for the boat to "find" when loading.

As far as a second shorter bunk outboard for stabilization, agree with you that they are better to have if you have the room for them.

My 2c,

Mark

 

[shark1600]

Re: Setting up new bunk trailer

I have a 17'4" boat and have 6 bunks on my trailer, thought pic might help you.​

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[Texasmark]

Re: Setting up new bunk trailer

I have a 17'4" boat and have 6 bunks on my trailer, thought pic might help you.​

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Looks great to me. Lots of bunks, 3 cross members, light boat.....whadda deal.

Mark

 

[nonimike]

Re: Setting up new bunk trailer

Hi ,
The above information is great , but I'm still a little confused with my trailer .

I recently purchased a Quicksilver 620 Pilot House and had to buy a second hand BUNK trailer sepearately and was wondering exactly where the two bunks should be positioned beneath the boat .

Please see attached photos , do the bunks need to be moved INWARDS into the red marked area or where exactly should I position them to best support the boat ?

I would be extremely grateful for any help re. the above .

Many thanks ,

Mike .