Hull deflection while on trailer

[JackBronson]

Was sitting on the stairs looking at the boat on the trailer and noticed that where the boat sits on one roller in particular the hull seems to have some flex in it. Its not a lot it seems (1/4" over a 15" straightedge maybe) but it made me wonder how much deflection (?) of the hull where it sits on the roller is too much? I imagine the hull must have some flex but does it flex more as the boat ages and does / should it become a concern? This is a 1987 StarCraft 19' bowrider.

 

[smokeonthewater]

are you SURE it's flex and not a dent?... MOST roller trailers I have encountered have very little pressure per roller.... I could grab any of the rollers on my 6000 lb carver and pull it away from the hull by hand enough to slide a hand between the roller and hull.... when released the roller was uncomfortable on the hand but not painful.

for an average divide the weight of the hull by the number of rollers

 

[JackBronson]

No Title

Nope, not sure however both sides are similar. I'd have to put it back in the water and get underneath and measure and its too cold now without a wetsuit for that.

Anyway, its both sides up front outer rollers.

I have 16 total rollers over 4 assemblies. This is an 87 EZ Loader and these rollers don't flex. They are all hard against the boat.

 

[Grub54891]

Mine had the same thing going on. 1985 larson. The foam was wet,stringers rotted,everything. All replaced and I'm getting rid of the rollers,putting bunks on instead,more surface area is better.

 

[JackBronson]

grub, do you recall how bad the deflection was? was it blatant? I ask because I wonder how much this might be an indicator of issues with stringers and foam. I have no access to see any of that, and quite frankly I'm not interested in ripping into such a project at this stage of my existence.

thanks.

 

[smokeonthewater]

this is an aluminum boat right? if so then no rotten stringers tho it could have wet foam making it heavy....


Look at your winch post setup... if the winch is pulling down on the bow eye that could cause this....If it's both sides it isn't likely to just be a dent..... The rollers DO move on that trailer... in order to move on down the other 3 on the same truck will all move up to a lesser amount..

While I wouldn't be overly concerned at this point assuming it is indeed aluminum you CAN add more rollers to better support the boat... One option is adding keel roller(s) to the cross member(s). Another is converting the front trucks to 6 or 8 rollers each.

One more option is if your trailer has the length to move the rear cross member back and then move the boat back that will transfer some weight off of the front trucks and on to the rear trucke NOTE you would also need to move your axle back to maintain tongue weight....

You can VERY easily check for dents without putting the boat in the water.... either roll it back a couple feet on the trailer OR simply put a jack under the keel near the front cross member and raise it an inch ir so off the rollers NOTE the trailer must be hitched to your truck or car for either of these methods.

 

[ken51k]

You should not see anything like that even on a roller trailer. The two things that I think of that would cause this are either the boat is to heavy for the trailer, not enough rollers to support the boat properly or you have rotten stringers. This is an older boat so I would check for moisture. Get a moisture meter or drill some small holes in the top of the stringers near this area and see if the wood comes out wet.Use a long small diameter drill then fill the holes.

 

[JackBronson]

Smoke, sorry it's fiberglass (I forgot that for most boaters Starcraft = aluminum). That would explain your dent question, because I was puzzled about fiberglass denting but went with it anyway.

I'm guessing a stringer issue. Ken is likely right. Older boat. Oh well.

Thanks to all for the replies.

 

[smokeonthewater]

Ok being a glasser it is heavier... it MAY not be rotten get it on a scale.... waterlogged = HEAVY so we can get an indication from weight... I would say that you don't have enough rollers for that glass boat..... Yon MAY not even HAVE a stringer where the deflection is so it may not be a rot issue at all.

 

[Grub54891]

Mine had 16 rollers,17' boat,fiberglass. Noticed that 2 rollers were indenting the hull near the aft 3rd of the hull. It was obvious that I had issues. Now the boat is almost done with the rebuild,and it'll be better than before,I shouldn't have to add bunks but its for peace of mind in my case. Besides,a few rollers are getting bad,so why bother with them.

 

[bonz_d]

. Besides,a few rollers are getting bad,so why bother with them.

Why, so you don't end up like Expidia and changing them 3 times in 7 seasons. When I changed trailers under my Lund I picked up a 1989 Spartan roller trailer which to this day still has all the original wobble rollers on it. So that's what? 25 years on one set of rollers!

 

[dozerII]

2000 lb boat if it's dry? 16 rollers 4" wide 1/2" contact surface with the hull = 32 square inches of surface area for the hull to sit on or 62.5lbs per roller. If there is no support behind the fiberglass is has to deflect.

 

[Grub54891]

I've only repaired the bunks on my other boat once in 20 years. Only because a car hit it when sitting empty.