Please help noob with new boat transom question

[MAC ATTACK]

Have not posted here in a while, but am looking for help on a (hopefully) simple question. I am looking at the 2012 Sea Chaser 18 RG. Never owned a CC or Bay/Flats boat.

I am going to attempt to attach pics, but my question is on the transom engine mount cut-out. It seams that the 2012 Sea Chaser 18 RG has a much lower opening than the 2008 18 RG. Can anyone explain to me the good/bad or reason for the lower opening?

I have reviewed these boats, and due to limited budget/storage/tow vehicle I am pretty sure for now this could be the boat for me. Plus I am about 1 hour from the manufacturer.

 

[pckeen]

Re: Please help noob with new boat transom question

There are three basic motor shaft lengths - short shaft (approx 15"), long shaft (approx 20"), and extra long (approx 25"). The cutouts on the back of boats are designed to take a motor of a particular size. This link will take you to a diagram comparing the shaft size on a motor to the transom height and how you measure them. Motors are usually stamped with a code that will identify them as a long, short or extra long shaft.

Changes in transom height are done so that the boat can accept a particular size of motor.

 

[Georgesalmon]

Re: Please help noob with new boat transom question

Couple of reasons. Hull deeper on one of them? Typical OB's are 15" (not so common anymore) 20" is kinda normal. 25" is also out there along with a few 30" motors. Measure the verticle distance from the bottom of the hull to the top of the transom cutout and what you find, clost to 20", close to 25", etc. (most hulls are not exactly 15, 20, 25) will tell you the motor length you need.

 

[MAC ATTACK]

Re: Please help noob with new boat transom question

Thanks! I am glad it was that easy of an answer. I believe the boats (08, 12) are identical, I just noticed the opening is lower on the 12. Not sure if it will cause any other issues, and wondering if it is for equipping the boat with smaller HP motors.

 

[smokeonthewater]

Re: Please help noob with new boat transom question

the shorter shaft motor CAN be swamped more easily in heave seas and the lower transom would be a little more prone to allowing a wave to enter the boat from the rear but these would be in the more extreme circumstances.

Not saying a 20" shaft is "bad" just that a 25" shaft is better in that regard. the shorter motor however may show some advantages in just being less obtrusive if you need to pass lines over it or whatever.

 

[H20Rat]

Re: Please help noob with new boat transom question

the shorter shaft motor CAN be swamped more easily in heave seas and the lower transom would be a little more prone to allowing a wave to enter the boat from the rear but these would be in the more extreme circumstances.

Not saying a 20" shaft is "bad" just that a 25" shaft is better in that regard. the shorter motor however may show some advantages in just being less obtrusive if you need to pass lines over it or whatever.

Except it never works quite that well. Its rare to safely get 5+ inches of range of mounting on a transom, so the 25" shaft motor isn't going to sit 5" higher. Its far more likely prop is just 5 inches deeper in the water. In the OP's case, a long shaft on that one boat would end up with a REALLY deep prop, and no way to raise the motor enough without a jackplate to get it to the correct running height.

 

[MAC ATTACK]

Re: Please help noob with new boat transom question

All good points. With that being said, it appears this boat is set up for a shorter shaft, which is ok since motor has not been purchased yet. But..... will the shorter transom difference cause me issues down the road? I have seen many boats like this while researching, but cannot think as to why one would prefer one transom height over the other. The specs claim a 12" draft, but that does not take into account intended use, which will primarily be lakes and flats.

Have a buddy with a Sea Boss that has the shorter transom, it seems to be a personal preference, use and motor height intrusion to casting/trolling etc.

 

[Georgesalmon]

Re: Please help noob with new boat transom question

Someone already said that a longer shaft motor and thus a higher transom might/could be safer in following seas. That's why there are a few 30" so called saltwater motors out there. They are mostly in high HP engines I think. When I got my kicker engine I opted for the longer shaft because with the deep V high dead rise I have on my boat I needed some extra length to get into good water out to the side. I did have to raise the transom a bit for it, but my thoughts were that if I get a boat with a higher transom someday I won't have to buy another kicker.

 

[crabby captain john]

Re: Please help noob with new boat transom question

What was said on a following sea is true. For lakes and flat water it is of little to no concern. Would not be my choice for the Great Lakes or Atlantic though.

 

[smokeonthewater]

Re: Please help noob with new boat transom question

Except it never works quite that well. Its rare to safely get 5+ inches of range of mounting on a transom, so the 25" shaft motor isn't going to sit 5" higher. Its far more likely prop is just 5 inches deeper in the water. In the OP's case, a long shaft on that one boat would end up with a REALLY deep prop, and no way to raise the motor enough without a jackplate to get it to the correct running height.

Noooooooo
a 25" motor on a 25" transom will sit 5" higher.... Not talking about mis matching stuff

 

[dingbat]

Re: Please help noob with new boat transom question

I'm guessing they lowered the transom (looks like 5") to lower the overall profile of the motor and facilitate the use of a 20" leg and/or a jackplate.

FWIW: The splash well still looks to be the same height.