Adjusting Trailer Bunks to Avoid Thru-Hulls

jason78

jason78

Active Member
TECHNICAL Contributor
Sep 3, 2008
3,662
Fort Mill, SC / Lake Wylie
Boat Info
1997 20 Outrage
Engines
200 Merc Offshore
As I continue to evaluate trailering options for my 280DA, one possibility that has come up is borrowing a trailer since I have had several offers for that. My concern initially with doing this was whether or not the bunks would miss my bottom thru hulls (I have a bunch- 5 to be exact). I have heard when people order trailers they sometimes have it adjusted so the thru-hulls don’t rest on the bunks. Obviously it would not be practical to borrow a trailer and adjust the bunks then move them back.

After thinking about it, I realized that all the local mechanics and dealers I have seen just have “shop trailers” they use to move boats around and take them in and out of the water. As far as I can tell they do not do any adjustment of the bunks before putting a boat on.

What are the concerns with thru hulls resting on the bunks? I am not sure what mine are but I have seen some that just have a flange with a hole in it (similar to what is on the side of the hull for bilge pump, etc) and some have a raised grill style thru hull.

Obviously don’t want to risk damage but it seems to be working fine for the mechanics and dealers I have seen do this. Just would like to get thoughts and comments.

Thanks
Jason
 
I keep my boat on a lift. The generator thru hull rests on a bunk. Same thing on my trailer. I have taken the boat to Canada and back a couple of times without any issues.
 
Last edited:
My macerator through hull rest on a bunk of the trailer. I'm not worried about it.
 
The mushrooms are no big deal. The scoops could pose a problem, especially if it's on a board that is right over a support (the board won't give). It's not a "guaranteed" problem... but it's best to avoid it.
 
jason78 said:
As I continue to evaluate trailering options for my 280DA, one possibility that has come up is borrowing a trailer since I have had several offers for that. My concern initially with doing this was whether or not the bunks would miss my bottom thru hulls (I have a bunch- 5 to be exact). I have heard when people order trailers they sometimes have it adjusted so the thru-hulls don’t rest on the bunks. Obviously it would not be practical to borrow a trailer and adjust the bunks then move them back.

After thinking about it, I realized that all the local mechanics and dealers I have seen just have “shop trailers” they use to move boats around and take them in and out of the water. As far as I can tell they do not do any adjustment of the bunks before putting a boat on.

What are the concerns with thru hulls resting on the bunks? I am not sure what mine are but I have seen some that just have a flange with a hole in it (similar to what is on the side of the hull for bilge pump, etc) and some have a raised grill style thru hull.

Obviously don’t want to risk damage but it seems to be working fine for the mechanics and dealers I have seen do this. Just would like to get thoughts and comments.

Thanks
Jason
Click to expand...
It's preferable that none of the thru hulls are on the bunks. Even the flatter ones concentrate a load in that area. People do it but it's not the best way go.
 
I believe it is a non-issue!
 
As you load the boat on the trailer, could you have some pieces of 1x6 and 2x6 handy to use to "prop up" the boat in case the trailer does hit any of the thru-hulls? You'd want to have some carpet scraps handy to protect the bottom of the boat.

It may be a non-issue, but why take the chance? The hull was designed to bear the load of the boat spread out over wide areas, not concentrated in small spots.
 
The bunks are carpeted and the bunks themselves are pressure treated pine, a softwood. The only thing that I notice is that the thru-hulls make an impression in the carpet. And I would expect that the wood fibers also give. My boat is loaded on lift bunks constantly during the year and there is no issue. And consider that the boat is sitting on the lift bunks 99.9% of the time. And, it has been for over seven years.
When you load the boat on a trailer, the thru hulls are not going to touch until you start retrieving the boat.
Sorry, I just don't think that it is an issue.
Of course, you don't want to take a chance on something if you don't have to, but, is it feasible to locate the bunks so that thru-hulls won't rest on them?
If I went one way on my trailer or lift, I would be too far out. Go the other way and I would probably be into the AC thru-hull. And then there is the other side - the stinky thru-hull to deal with.
Has anybody ever heard that someones boat had to be repaired because of thru-hull resting on a bunk? I haven't.
 
Last edited:
JerryS said:
The bunks are carpeted and the bunks themselves are pressure treated pine, a softwood. The only thing that I notice is that the thru-hulls make an impression in the carpet. And I would expect that the wood fibers also give. My boat is loaded on lift bunks constantly during the year and there is no issue. And consider that the boat is sitting on the lift bunks 99.9% of the time. And, it has been for over seven years.
When you load the boat on a trailer, the thru hulls are not going to touch until you start retrieving the boat.
Sorry, I just don't think that it is an issue.
Of course, you don't want to take a chance on something if you don't have to, but, is it feasible to locate the bunks so that thru-hulls won't rest on them?
If I went one way on my trailer or lift, I would be too far out. Go the other way and I would probably be into the AC thru-hull. And then there is the other side - the stinky thru-hull to deal with.
Has anybody ever heard that someones boat had to be repaired because of thru-hull resting on a bunk? I haven't.
Click to expand...
I have seen pictures of damaged clamshell strainers and I have heard of people rebeding thru hulls because they leaked. How many where caused by trailer bunks I don't know.

Someone should call SeaRay and get their opinion. Maybe call a quality trailer manufacturer also.
 
Yeah, I wouldn't put a clam shell on a bunk. It would be a good idea to check with mfr's to see if they have any comment. Couldn't hurt!
 
Thanks for all the replys so far. As far as I can tell the general opinion is that best practices would dictate the bunks be adjusted to avoid the thru-hulls, however limited trailering should be OK with some of the thru-hulls resting on the bunks as long as you have the "mushroom" style and not the clamshell style?

I have sent an email to Sea Ray but I think I know what their answer will be.

Thanks for all the ideas and please keep them coming.

Does anyone with an 05 280DA have any idea what style I have? I am pretty sure they are mushroom but can't be certain. Every time my boat has been on a service trailer, I have not been able to see all the thru hulls, possibly because they were resting on the bunks.
 
jason78 said:
Thanks for all the replys so far. As far as I can tell the general opinion is that best practices would dictate the bunks be adjusted to avoid the thru-hulls, however limited trailering should be OK with some of the thru-hulls resting on the bunks as long as you have the "mushroom" style and not the clamshell style?

I have sent an email to Sea Ray but I think I know what their answer will be.

Thanks for all the ideas and please keep them coming.

Does anyone with an 05 280DA have any idea what style I have? I am pretty sure they are mushroom but can't be certain. Every time my boat has been on a service trailer, I have not been able to see all the thru hulls, possibly because they were resting on the bunks.
Click to expand...
If no one answers by the time I get home tonight, I will snap some pics of the bottom.

On another note, my biggest project to complete ASAP is trying to fab up something on the front of the trailer so I don't have to fight with the anchor hitting the bow roller at low tide:smt021:smt009 It's a real pita and borderline embarrassing at the ramp during low tide having my wife backing the truck up and pulling forward and winching and repeating:smt021
 
I heard back from Sea Ray. As I expected, they advised it is not recommended to have the thru hulls resting on bunks, however, in the event that it cannot be avoided, check for leaks after it goes back in the water.

Translated, that sounds to me like- Adjust the bunks if you can as a best practice; if that is not possible it should be OK but we cannot tell you that for obvious liability reasons so be sure if you do have thru-hulls on the bunks, check for leaks afterward.

Jason
 
Donnie, if you figure something out - show us. There's a ramp I use in Maine that is extremely steep and I do that same "dance" that you are doing!
 
I think your "translation skills" are spot on, Jason. :smt001
 
Lazy Daze said:
Donnie, if you figure something out - show us. There's a ramp I use in Maine that is extremely steep and I do that same "dance" that you are doing!
Click to expand...

Same thing here!

Jason, I trailer my 280DA and also keep it on a boat lift. I have my bunks situated on both so that none of my thru hulls rest on the bunks. I think my bunks measure about 49-50" apart to find that sweet spot.

Tom
 
Lazy Daze said:
Donnie, if you figure something out - show us. There's a ramp I use in Maine that is extremely steep and I do that same "dance" that you are doing!
Click to expand...


Show Me Too, Show Me Too. :smt038

You mean the power to the right, slip the anchor by the roller, then power to the left to center it dance?
 
Last edited:
I bought a used trailer to carry my 1990 290 Sundancer. The thru-hulls were resting on the bunks. I launched it several times and towed it 500 miles before I got the bunks adjusted. In the meantime it tore the carpet off and chewed up the bunks themselves. My suggestion is to adjust the bunks.
 
Went home today and brought the boat to my shop. I will have my fabricator working on it the rest of the week. I am open to any and all suggestions. I know I have to account for the flex in the aluminum trailer so this will be interesting...lol Here are some pics of the thru hulls. I'm glad you wanted these! I see my A/C thru hull is crushed! I need a new one:( The grill is busted and looks like it has been this way for a while!

7270f5fb.jpg


4228bad5.jpg


efffec26.jpg
 
Thanks for posting those pics Donnie!

You know I was watching the forklift operate the other day and it occured to me the same issue must be faced with having a boat forked up out of the water.

I have never seen a fork operator pay a whole lot of attention to exactly where they lift so I am sure these thru-hulls get lifted on all the time by forks. This could be potentially be more of a problem because many of the forks I have seen have a hard rubber cover on them which would offer virtually no flex whatsoever like a trailer bunk would.
 
You must log in or register to reply here.

Forum statistics

Threads
113,167
Messages
1,427,707
Members
61,078
Latest member
96SR40EC
Back
Top