Remember that the original FBs had 70 or 90 hp engines and ran quite well. Modern big engines will lure rebuilders to put a huge engine on the boat. Our experience through many rebuilds is that a 150 2-stroker like Merc Opti or maybe the Rude is the perfect engine for the hull. A heavy 4 stroke is exactly that, heavy and changes the weight distribution. I have seen some guide boats with 150 Hondas but not sure if they compensated for the weight by moving things forward.
The Suzuki df140 is 410lbs which is only 20lbs heavier than an evinrude etec 115. I’ll take 25hp for 20 extra pounds and not having to buy oil. Anyone else run a df140 on a flatback?
Quote from: RickK on May 20, 2020, 07:09:52 PMRemember that the original FBs had 70 or 90 hp engines and ran quite well. Modern big engines will lure rebuilders to put a huge engine on the boat. Our experience through many rebuilds is that a 150 2-stroker like Merc Opti or maybe the Rude is the perfect engine for the hull. A heavy 4 stroke is exactly that, heavy and changes the weight distribution. I have seen some guide boats with 150 Hondas but not sure if they compensated for the weight by moving things forward.My plan is to put a bracket and a Suzuki df140 on the back. As far as I can tell they’re very small and light for the HP, especially for a 4 stroke. I think a 140 is more than enough power and with the flat back it should jump up on a plane with minimal effort. Is there any rule of thumb with new tank placement? I want to go up forward from the middle of the boat. Like one end under where the console will be and the rest running forward. It’s going to be a 55gal poly tank. And I appreciate the above advice as fast as making plans and drawings. I plan on keeping detailed records and putting pictures on a thumb drive for future reference. Read through the history page last night as well... is it possible my boat is earlier than I thought? Being a C+S? Thanks for everything Rick and company!
Quote from: BlackHagdon222 on May 20, 2020, 10:10:06 PMQuote from: RickK on May 20, 2020, 07:09:52 PMRemember that the original FBs had 70 or 90 hp engines and ran quite well. Modern big engines will lure rebuilders to put a huge engine on the boat. Our experience through many rebuilds is that a 150 2-stroker like Merc Opti or maybe the Rude is the perfect engine for the hull. A heavy 4 stroke is exactly that, heavy and changes the weight distribution. I have seen some guide boats with 150 Hondas but not sure if they compensated for the weight by moving things forward.My plan is to put a bracket and a Suzuki df140 on the back. As far as I can tell they’re very small and light for the HP, especially for a 4 stroke. I think a 140 is more than enough power and with the flat back it should jump up on a plane with minimal effort. Is there any rule of thumb with new tank placement? I want to go up forward from the middle of the boat. Like one end under where the console will be and the rest running forward. It’s going to be a 55gal poly tank. And I appreciate the above advice as fast as making plans and drawings. I plan on keeping detailed records and putting pictures on a thumb drive for future reference. Read through the history page last night as well... is it possible my boat is earlier than I thought? Being a C+S? Thanks for everything Rick and company! How big of a bracket? Adding 100 lbs of extra motor weight and offsetting that from the transom will create a lever effect on the boat. We usually see porta brackets used and they offset I think like 25". As for the poly tank, they grow in all directions by 1-2% when gasoline is poured into them, they expand and don't contract, so allow for that movement when you design the tank coffin.
As for fuel tank coffin how do I get it locked down tightly AND give it space to expand? Like just leave a few inches side to side and front to back? I would have made it too tight if you hadn’t said that so thank you.
Quote from: BlackHagdon222 on May 21, 2020, 07:56:13 AMAs for fuel tank coffin how do I get it locked down tightly AND give it space to expand? Like just leave a few inches side to side and front to back? I would have made it too tight if you hadn’t said that so thank you. Note that the tank grows in all directions, even top to bottom. but it only grows once. So measure your tank and add 2% in each direction and make your coffin that big. On my tank I had 2 ribs going across the top so I used a piece of composite that fit between the ribs to anchor the tank. My poly tank is one with a very weird shape. Like follows the bottom of a 12 degree hull. but has a flat top. So the sides are only a couple inches high.
