Bunk Board Length

[asm_]

Hi,

After reading so many posts, books and articles (rumors?) on the subject bunk board length for supporting hull, almost everyone agree the bunk board should support the hull all the way to the transom edge. This is to reduce of possibility of forming a "hook" at the aft hull.

Now, if the said theory is true, why does most boat mfg/dealer always fit the boat to the trailer with the bunk few inch short of the transom? Am I missing something?

B

 

[Outsider]

Re: Bunk Board Length

Am I missing something?

A trailer that fits the boat properly, maybe?

 

[raven7]

Re: Bunk Board Length

Possibly so the bunks don't hit a speedometer pitot tube or transducer mounted on the transom if you have a little to much speed when loading the boat.

 

[JB]

Re: Bunk Board Length

The board should be twice as long as from the middle to one end, and that end should be directly under the transom.

As Outsider suggests, that would be a trailer that fits the boat.

 

[Home Cookin']

Re: Bunk Board Length

I doubt a few inches matters (in this discussion). Rollers don't go to the transom edge, either--too risky of rolling off. A good transom should be able to handle it.

 

[JimS123]

Re: Bunk Board Length

In the old days, I've seem many a hull ruined because of improper trailer setup. As a matter of fact, my early inexperience and hurriedness caused the nicest hook you would ever want to see....LOL.

These days, "most boat dealers" weren't around then, so with lack of experience they simply don't know what to do. My last 2 boats were setup my ME, because I don't trust any boat dealer that is still wet behind the ears.

If you are talking about an I/O, a few inches short probably isn't a problem because the main weight (engine) is located forward of the transom. Now that's provided that the boat isn't kept outside all year long and has lousy integrity because the stringers and deck are all rotted ot.

But if you have an outboard, you better have the bunks right to the transom. They don't have to stick out beyond, so there is no interference with speedometers or transducers.

Also, for an outboard, if you insist on bunks instead of an easy-to-load-never-a-problem all roller trailer, I would still add a large keel roller right at the transom. All my current boats (except the jetski) have an aft roller located within an inch of the transom. No way the boat can "roll off" since the winch stand serves as the forward stop.

But in reality, you can set up your trailer any way you like. However, don't post a question in a year or so about how to stop the boat from porposing!

 

[monk-monk]

Re: Bunk Board Length

WOW, i have to keep this Post going...i was searching Posts for power loading my boat...the boat ramps at my favorite lake are full of holes, so you have to get away from the slip to get a good level trailer...my trailer does not have True Rollers, so when i tried to power load today, the bottom of the hull, just back from the bow, was hitting that front rubber support on the trailer and it would not let the boat push all the way up on the trailer....great Post here...This is the stuff i need to learn !

 

[asm_]

Re: Bunk Board Length

Thanks for all the reply!! I guess I'm not the only one confused on the subject.

 

[90stingray]

Re: Bunk Board Length

Hi,

After reading so many posts, books and articles (rumors?) on the subject bunk board length for supporting hull, almost everyone agree the bunk board should support the hull all the way to the transom edge. This is to reduce of possibility of forming a "hook" at the aft hull.

Now, if the said theory is true, why does most boat mfg/dealer always fit the boat to the trailer with the bunk few inch short of the transom? Am I missing something?

B

I think the boats are not properly loaded on the trailer... you can winch it too much and sometimes not enough. Give it a try... crank it on some more. I prolly have 4" of play on my rig. But luckily i know where to stop winching to get her just right

 

[asm_]

Re: Bunk Board Length

I doubt a few inches matters (in this discussion). Rollers don't go to the transom edge, either--too risky of rolling off. A good transom should be able to handle it.

Interesting point.

I was at a boat show earlier today. 8 out of 10 boats that were on the trailer at the show has their bunk board not supporting the transom, including outboard motor models. Almost all of them had the bow ring all the way cranked up against the bow stop. Therefore, there is really no more room for the boat to be move forward. Some of the trailer even has none-adjustable bow stop. This means the trailer is factory built to fit the boat. Of course, this further make me believe, perhaps, having the bunk board supporting the transom may not be as big of deal as I originally believed.

I'm hoping some mfg or boat builders would chime here to shine some light on the subject here.

B

 

[phillnjack2]

Re: Bunk Board Length

The problem is everyone nodays trying to make everything that lit bit cheaper.
Bunk trailers should be used so the bunks only support the boat as in balance.
There should always be keel rollers to take the main weight of the boat, and leave the bunks to just keep level.
Bunks shloud go atleast 2 inches out the back of the boat to stop hull deformations. (hooks).
This is a must on tri hulls like boston whalers and dell quay type boats.
As said above, too many boat sales people realy dont know as much as most boat owners, and the trailers
are not set up properly.
As for trailer manufacturers, a friend recent had a trailer custom made for his boat, they were given every
detail you could want, even a diagram from boat makers and all the degrees along the hull etc.
The trailer came to him looking great, but would of been dangerous to use the way it was set up.

Dont always think the so-called expert knows what he is talking about, ask someone with genuine experience
and then think about the if nots,what if's, and why nots.



phill

 

[Guest]

Re: Bunk Board Length

This trailer needs its bunks replaced before the boat is loaded again, they are rotted badly from obvious salt water exposure. But is the orientation of the bunks adequate? When I do replace them, I was going to just leave the boards 8ft and allow them to protrude forward for more support. But do I really need those roller bunks if I put a support roller on the rear center there?

 

[bonz_d]

Re: Bunk Board Length

The problem is everyone nodays trying to make everything that lit bit cheaper.
Bunk trailers should be used so the bunks only support the boat as in balance.
There should always be keel rollers to take the main weight of the boat, and leave the bunks to just keep level.
Bunks shloud go atleast 2 inches out the back of the boat to stop hull deformations. (hooks).

phill

I have to disagree. I have seen too many posts here in the resto section of hulls that do not have a keel stringer and therefore do not have the strength in the keel to support the majority of the hull weight by sitting on rollers. Also there are today too many trailers that have no rollers at all. Full Bunk Trailers! On these trailers the bunks extend almost the entire length of the bottom and on heavier boats there are more than 2 bunks. Also as pointed out, on Full Roller trailers the most aft rollers extend well past the last keel roller and are also a few inches short of being even with the transom.

I now have a Roller trailer and I really do not think I would want any portion of the last roller extending out past the end of the trasom!

 

[asm_]

Re: Bunk Board Length

Thanks for your post, bonz_d. One of the article I was reading did mention the weight of the trailer should not be rested on the keel. All weight must be support by bunks. Of course, after reading phillnjack2's post, I was a bit confused. It now make sense that some boat are built differently with keel stringer. Now, this may be a dump question, but can I tell if a boat has keel stringer?

B

 

[bonz_d]

Re: Bunk Board Length

Thanks for your post, bonz_d. Now, this may be a dump question, but can I tell if a boat has keel stringer?
B

A good question though I do not have an answer. W/O knowing a builders designs I guess the only way to tell for sure is to remove the deck. From what I have seen recently my guess would be that most new smaller boats do not incorperate a keel stringer and that many only use two stringers total.

 

[JimS123]

Re: Bunk Board Length

The keel should be the strongest part of the bottom, regardless whether it has a stringer there or not. If your keel won't support the full weight of the boat, you have a big problem.

Go to any marina and see how they store boats in the yard that are not on trailers.

Boats are expensive. To make them somewhat palatable to the average guy the dealers skimp on the trailer. Heck, you'll only own the boat a few years anyway, so why should they care. (even if they had half a brain)

The last 3 boats I bought did not come with the trailer the dealer suggested. I upgraded at considerable extra expense.

Post #11 above has it all right. Only those in the know agree with that, unfortunately.

 

[Guest]

Re: Bunk Board Length

I have decided to remove the set of roller bunks, most of the rollers were not properly against the hull and have worn unevenly. I will make sure the transom is properly supported by adding a support/guide roller to the rear where that built on transom saver is. Another needs to be added from what I have seen on the few other photos of similar Skeeter Hawks on Dilly's ive seen, to help support the bow.

 

[bonz_d]

Re: Bunk Board Length

The keel should be the strongest part of the bottom, regardless whether it has a stringer there or not. If your keel won't support the full weight of the boat, you have a big problem.

Go to any marina and see how they store boats in the yard that are not on trailers.

The last 3 boats I bought did not come with the trailer the dealer suggested. I upgraded at considerable extra expense.

Post #11 above has it all right. Only those in the know agree with that, unfortunately.

Sorry, though I still disagree yet agree on one point. Yes the keel should be the strongest part of a hull. Unfortuneately from what I have witnessed modern building technics do not allways follow that. Also your only evidence to your statement is to go any marina and look how they store boats w/o trailers. Now I do not know how it's done in your neck of the woods but here in the Midwest around the Great Lakes those boats are placed on bunk cradles and then placed up in a rack. Those bunk cradles have no keel support and those boats are stored like that for months on end.

As to your last statement I take that as just one persons opinion and as you can find on this forum opinions differ greatly. These people can't even agree on the issue of trailer types and which is best let alone on how to set them up or how to use them.

 

[JimS123]

Re: Bunk Board Length

Also your only evidence to your statement is to go any marina and look how they store boats w/o trailers. Now I do not know how it's done in your neck of the woods but here in the Midwest around the Great Lakes those boats are placed on bunk cradles and then placed up in a rack. Those bunk cradles have no keel support and those boats are stored like that for months on end.

As to your last statement I take that as just one persons opinion and as you can find on this forum opinions differ greatly. These people can't even agree on the issue of trailer types and which is best let alone on how to set them up or how to use them.

Yup, its only an opinion. Believe me or the other guy, it's all up to you. In addition to my expert boatman qualifications (LOL) is that I'm also a teacher (not of kids in grammar school, but of Engineers in a factory setting), so my motivation is to help people, not steer them in the wrong direction like a puter hack that might send out a virus.

I'm in the Eastern Great Lakes region and over here the marinas lay out several cement blocks in a row, top them with a toobafore so it doesn't scratch, then put the keel right on them, with the last one located right under the transom. Add two stands at the transom so they don't fall over and viola you got good support.

 

[bonz_d]

Re: Bunk Board Length

Yup, its only an opinion. Believe me or the other guy, it's all up to you. In addition to my expert boatman qualifications (LOL) is that I'm also a teacher (not of kids in grammar school, but of Engineers in a factory setting), so my motivation is to help people, not steer them in the wrong direction like a puter hack that might send out a virus.

I'm in the Eastern Great Lakes region and over here the marinas lay out several cement blocks in a row, top them with a toobafore so it doesn't scratch, then put the keel right on them, with the last one located right under the transom. Add two stands at the transom so they don't fall over and viola you got good support.

So what "other guy" are you refering to? What constitues a puter hack?

Guess on the other side of the Great Lakes they do it differently. Yes I have seen what you describe with the very large boats only they are using Styrofoam instead of Concrete blocks.

Guess my next question to you then is in a previous post you refered to roller trailers over bunks and that a keel roller should be placed at the end under the transom. How would you do this with say a Spartan, Calkins or EZLoader where the end wobble rollers extend well past the end of the trailer bed?