Larson 206 sei O/B 1999

[nick57]

Hi there
Im new to the forum and boating.
I am in the process of trying to restore a Larson sei O/B.
Could anyone tell me what density foam is in the stringer system?
Is it the same as under the deck?
Also the transom measures 20" but if you go back along the hull 6" there is a drain plug which drops 3", so what size lower unit do I need. 20" or 25"
Thanks Nick

 

[JASinIL2006]

Foam should be standard 2 lb. variety; the strength is in the fiberglass stringers, not the foam.

 

[JASinIL2006]

I would add that on my '97 Larson, the fiberglass was REALLY thick in the engineered stringers. I can't imagine that the foam was there for much other than extra buoyancy in the event of capsizing. The foam certainly wasn't adding much strength to the stringers. (I know filling the larger cavities under deck with foam can help make everything more rigid, but the volume of foam in the stringers and bulkheads isn't enough to help much in that department.)

 

[Woodonglass]

Yup 2# foam is fine. It's jus the mold for the glass. Why do you ask? Are you cutting the stringers open? If so why? Not sure I can visualize your Transom/Hull question. Basically the lower leg is measured like this...

 

[JASinIL2006]

Actually, if the '99 Larson SEI is constructed the same as the '97, the foam wasn't even a form for the stringers/bulkheads; the stringers were formed in a mold (mine were even gelcoated!), then glassed to the hull, then fulled with foam through holes cut into the tops of the stringers.

At some point, I think they changed their manufacturing process such that the stringers were actually integral to the hull (rather than cast separately and added after the hull was built), but I am not sure when that change occurred.