building xf20

[jacquesmm]

I remember, thank you for posting and I am glad somebody still has fun with the boat.
There is more than one way to interpret my plans and yes, others have built the XF20 heavier and with more HP. I saw one in TX with a 200 HP engine on it . Bad trim at rest but the owner looked happy.

[MrPaul]

Thanks for the input Jacques. I'm having a great time with the build. It seems like a lot of people who built this boat were happy with the Yamaha 70 and I seem to remember Ken Owens mentioning that the 60 seemed a little short on power in his thread. I'm not a speed freak but I want good hole shot so I'll use a 4 blade prop. If I can get 35 mph I'll be happy. I know Yamaha 50 - 70 weigh roughly 250 pounds. My boat will hopefully look a lot like hunchs' but with a center console and built with 9mm okume. If you think the 70 is ovrerkill, please let me know.

[TomW1]

I know of several guys who have gone with the Yamaha 70 HP and this Power Tech multi cup prop in I believe a 13 pitch. http://www.ptprop.com/index.php?page=sh ... &Itemid=46 With a Bob's jack plate this will allow you to run very shallow.

Tom

[MrPaul]

Thanks Tom. I saw all the numbers you and George went over on the xxxf20 and it looked to me like that boat came out very nice. So are you saying the lower end of the pitch range is better for hole shot? I'm not too knowledgeable on these things yet and still haven't bought the motor so i don't know all the details/stats on a new f70 but this looks like the prop I'm looking for.

[TomW1]

Yes the lower pitch will give you two things a better hole shot and higher rpm's at top end. The Yamaha 70 tops oat at 6000 rpm's and you should be running at 5500-6000 rpms. This prop should give you both. I don't know whether you will need the 13 or 12 pitch, it will depend on the final weight of the boat and load you carry.

Tom

[MrPaul]

Thanks Tom. I don't know what it's going to weigh yet. I'm kind of building by the seat of my pants and haven't figured out all of the things I want to put on it yet. I know I want to keep the weight as low as possible but I've got to have a working live well, trolling motor, 2 in deck fish boxes, an in deck storage locker, etc... and I know that's going to add some weight. Should I assume the heavier the boat the shorter the pitch?

[MrPaul]

My transom is made of 2 layers of 1/2" Joubert Okume. My 1x12 clamping board is Honduran mahogany but it arrived last week and is only 7/8" thick. Will the transom be strong enough to support a 250 pound 70hp Yamaha 4 stroke motor or should I reorder the clamping board to be milled to exactly 1"?-- or....add another layer of 1/2 Okume to the inside of the transom? The tunnel has already been installed if that makes a difference. Any advice is sincerely appreciated.

[pee wee]

If the plans call for a 1x12, then you're fine with what you have. The common dimensions of a 1x12 are 3/4" thickness and width of 11-1/2".

[stickystuff]

You need to have at least a 2" thick transom. Plus or minus 1/8 inch wont matter.

[TomW1]

You are fine. An 1/8 won't matter in a solid piece of wood.